Well first off its an attachment, so it does not need bones, only correct size and placement.
I think you should figure those out yourself...
Anyhow, you will have a major problem with max 7 because i dont think it has an mdx exporter soooo.
you will probably have to export as a .3d file and convert from there to mdx or to obj then mdx.
From there you will probably have to edit the mdx by converting to an mdl and changing the texture to accept your skin for it.
Now for the skin, you will need to unwrap it in max or after max in some other program add a uvw map and learn to do it yourself.
As for animations i think your out of luck, with max 7 youd have to use somthing else for that.