Adding dimensions to attributes - Canada Post

Well, I could use a hand with this, I hope someone can help.

I use the Canada Post shipping module which calculates shipping based on the dimensions and weight of an item.

The attribute controller for items only has fields for adding weight, and none for overriding nor adding dimensions to the default size of an item.

Basically I have a costume tail,
http://www.n o r t hfur.ca/shop/index.php?main_page=product_info&cPath=97&products_id=383

(remove spaces in north)

By default it comes stuffed, which has large dimensions.
I'd like to start offering it unstuffed by default to significantly lower the shipping prices, but I still want it to have the option for it to be stuffed if someone wanted it this way. But to calculate shipping properly, it would need to either add or override the default dimensions of the item.

Are there any existing modules or patches that can add dimensions to attributes or have the dimensions of an attribute override the dimensions of an item?

Thanks for any help!

Exactly what I was looking for, come on, someone must have an answer, there can't be only two of us using Canada post

same question. dimensions (length, width, height) is importent to product. Why Zen cart doesn't provide this?

I created a new post before seeing this one... (http://www.zen-cart.com/forum/showthread.php?t=168889) did you anyone get a work around?