This is something new to me - I would love to know if their anyone out there that has had any kind of mating activities with a female sealion or seal? ;)

Can't say I've ever heared about it. Sealions are often very active animals which can be quite intimidating up close, while seals tend to be rather 'lazy' in comparison. I doubt either one would make a very willing mate, but it might be possible. Especially with sealions, I'd say you need an exceptionally good relationship with the animal or you run the risk of getting seriously hurt.

I have heard that Dolphins will accept a human male and will often masturbate by rubbing her vaginal slit against a trainers leg.

Female Sea lions are very similar to dogs (genetalia), like to be fingered, and have a pretty good sex drive. It's difficult if not almost impossible to achieve relationships with them in the wild as they tend to bite, and are quite strong. If you're lucky enough to befriend one, a sexual relationship can be quite rewarding.