Don't bother with the BGE gasket. Use the permatex high heat copper sealant.
Put a ring around the entire edge, cover with saran wrap (I think some people put some spray oil on the saran wrap to keep it from sticking), close the lid, and let dry. After drying, remove saran wrap, and trim any excess with a razor blade. Will make a great gasket.
Alternatively, I used the same sealant, but used it with the nomex gasket at the time. It's worked great, but I really didn't need to bother with the gasket while using the permatex sealant.