Are you able to set aside an entire weekend to shape Clover going into the crate? Shaping is extrmemely effective but it requires dedication, patience and utmost consistancey by the human part of the team

The struggle that is happening now is not great for you or Clover so it's best to start from scratch with an intensive re-education while she is still young (I'd not like to have to pick up an adult Boxer to get them into a crate). Sounds like there may be other things happening here as well, or Clover has had a bad experience with handling in the past?
Anyway, if you are interested, here is a rough guideline (I'd use a clicker for this but I guess you are not clicker training?):
Get lots of extrememly tasty treats that Clover just loves (even skip a meal so she is extra hungry). Pick a word you can say to Clover so you can pair that word with the great treat ('Yes' 'Great'). Say the word in an upbeat happy voice and give her a treat. Repeat 15 - 20 times in a row so she associates that word with the treat.
Next, head in the general vicinity of the crate and say the word and treat the minute she glances at the crate (try to position yourself so she can glance at the crate). When you treat hold the treat just in front of her so she has to reach toward it (and the crate) to get it - golden rule of training is position of reward. Don't be tempted to lure her into the crate as we want her to think of this on her own.
Keep saying the magic word and treating for glances at the crate - if she steps towards the crate (or even wiggles her toe closer) give her two treats. If she puts her nose in the crate have a party and give her several treats.
You need to do this in baby steps and keep the rate of reinforcement very high. Always say the word and treat her for any progress no matter how small. I'd be trying to get in a reward schedule of about 20 - 30 per minute for this first off (if she scratches, yawns or walks away, you need to split the behaviour down further so you can reward more. Keeping the reinforcement rate high is very important to assist learning). Do not give more than 2-3 reinforcements at any one step along the way to the final behaviour of walking into the crate, as it may make it difficult to move up to the next level of performance. Clover may get stuck offering this over-reinforced level.
That the rough idea - below are some more in depth articles on shaping that will enable you to work out a plan (writing out a plan really helps). Try the exercise several times a day for short sessions. The artilcles mainly clicker articles but instead of 'click' you can use your chosen word.
This is from a class handout we use:
What is Shaping?
Shaping is the process of rewarding parts of a behaviour you want until you get the final behaviour.
For example we want Fido to stand with his front feet on a box. We could sit and wait for hours until Fido accidentally happened to be standing with his feet on the box (which may never happen). Or we can shape little behaviours that will lead to standing on the box. This is called splitting the behaviour. Splitting the behaviour accelerates learning as it helps us to keep the dog's rate of reinforcement for correct responses very high.
We can split the front feet on the box into:
1. Looked toward the box
2. Moved head toward the box
3. Moved front paw toward the box
4. Moved four feet toward the box
5. Lowered head toward the box
6. Sniffed the box
7. Touched the box
8. Pawed at the box
9. Placed one front foot on the box
10. Placed both front feet on the box
At each stage we would click and reward the dog. To accelerate the shaping process, it is important to place the reward where you want the behaviour to occur. So when the dog was clicked for looking at the box, we would deliver the reward between the dog and the box. When the dog moved toward the box, we would deliver the reward above the box. When the dog sniffed the reward we would deliver the reward on the box. If the dog wasn't offering to touch the box with its foot we could reward a sniff or nose touch by delivering the reward up higher above the box. The moment the dog touched the box with its foot we would click again and deliver another reward above the box to reinforce the feet on the box. Use your release word to indicate the exercise is over. < rest cut - really long >
Online articles:
10 Laws of Shaping
http://www.clickertraining.com/trai...&itemnumber=3&salesitem=ten_laws_of_shaping_s
Crate Training (with shaping)
http://www.clickersolutions.com/articles/2001/crate.htm
101 things to do with a Box (or maybe crate

)
http://www.clickertraining.com/training/clicker_basics/index.htm?loaditem=101_w_a_box&itemnumber=8
Shaping Behaviours
http://www.dogseast.com/shaping.htm
Operant Conditioning and Shaping
http://www.dogscouts.com/clicker.shtml
The art of shaping (this is pretty neat - something I plan on trying with my Boxers)
http://www.dogscouts.com/artofshaping.shtml
Your plan might look something like:
Step 1: Dog looks toward crate. I click and reward between the dog and the crate.
Step2: Dog steps toward crate. I click and reward between the dog and the crate.
Step3: Dog takes two steps toward crate. I click and reward in the entrance of the crate.
Step4: Dog walks toward crate. I click the instant a foot touches the crate, reward just inside the crate door.
Step5: Dog walks over to the crate. I click the instant a foot touches the inside of crate, reward in the crate.
Step6: Dog steps in the crate. I click and reward in the crate
Step7: Dog places most of body in the crate. I click and reward in crate.
Step8: Dog places all of body in the crate. I click and reward in crate and release the dog from the crate.
Step9: Dog quickly re-offers going in the crate. I click, reward and release the dog.
Step10: Dog stands in crate. I reward regularly to keep dog in the crate.
Final Behaviour: Dog walks into crate and turns around and waits in the crate.
Sharon