I never tried a kit from Cabelas. From what I remember, they don't let you select the correct size form. They just send one. I'm not sure on this but that's what I think I remember.
I used a kit from WASCO. It is pretty easy to understand the directions. The skinning of the squirrel is the hardest part, especially the feet and toes.
The WASCO kits give you everything except the form. You choose that seperate. That way you get one that fits the squirrel and the pose you want. Forms range in price from about $12 to $25. There are many to choose from.
McKenzie also has forms.
http://www.taxidermy.com/
http://www.mckenziesp.com/taxid_store/catalog_category.asp?CategoryID=%7B7AE5B5C3%2D5025 %2D49F0%2DA420%2D9DBFC834D017%7D&mscssid=J92HM 9L9QT229M91G110FR8H4P7VCN9C