Reading a list mail about Squirrels in the US and deterring them from raiding the garden. Possums are just about as agile and while I have them around here - hear the boys swearing at each other - so far (fingers crossed) I've not had any hassles with them in the yard.
Anyway for what it's worth, quote from the post:
"Any way, we've tried oodles of things from Vaselining the posts, putting
out trays just for them, to cayenne peppering everything (our squirrels
must be Cajun). Mary Fran saw on the computer that a guy had stymied them
with a Slinky over the post. When the squirrel reached the slinky it did
what slinkys do. It 'opened up' and took the squirrel back down to the
ground. Over and over again, and the squirrel got real pissy because it's
tail was moving around like mad."
Worth a whirl perhaps.