http://www.renderosity.com/mod/forumpro/showthread.php?message_id=233700

A possum looks a bit like a giant rat.  Someone else was looking for rats in that thread and there are some leads on where to get some, including a ferret which would work.  You can also use Little_Dragons bushy tail.

I've never seen a possum but you should be able to make something very close using the resources in this thread and the ones in the thread I linked to.

"It is good to see ourselves as others see us. Try as we may, we are never
able to know ourselves fully as we are, especially the evil side of us.
This we can do only if we are not angry with our critics but will take in good
heart whatever they might have to say." - Ghandi