sorry for the double post... but:

:-| ,.... not funny. BTW I just planted my seedling high up in a tree i climb up there and saw a rotting knot where a branch used to be, the hole is about the size of a golf ball and the wood is really soft around that so hopefully little mary will grow and make buds for me ill post pictures some other time cause im real tired from climbing that damn tree. the plant will probably die with my luck
I doubt this will work well, the plant will be open to get any problems the tree has, as it is in direct contact with it, not to mention extreme lack of root space (Your roots need plenty of room to grow so the plant can get large.)
You need a large hole in the tree (at least 5 inches I'd say) and as big around as possible. Then I would cover the exposed tree with plastic of some sort and fill the hole with dirt.