Spandex is so thin that whatever adhesive you use will probably bleed though it. You're better off using thin neoprene as a cover material. That said, Bill's suggestion of 3M Super 77 spray is probably your best bet for success.

Brian,
I have not used Super 77 glue before. Is it similar to contact cement?

I use contact cement to glue cover my carved, closed cell foam seats, with 1/16" thick neoprene (SweetComposites.com)

The closed cell foam, also from Sweets, can be easily carved with a 3M paint stripping wheel. Finish shaping with a small disk of 36 grit by hand and then use finer grits to make the foam have a suede leather appearance.

A heat gun will give the surface a darker pearlized look.

All the best,
Rob