Mike, I bought a light seal kit from Jon Goodman who is a very nice guy and is sometimes here in the APUG forums. Instructions are included and I think you can do several SLR's with the kit. I did three Yashica Electro 35 cameras and it worked out very well. I think the kits are under $10.
He is also on Ebay but I don't know his used ID. His email is
I Hope this helps