Man, if its black mold stay the fuck away from that seat. People have died from inhaling its spores. If its the greyish kind, its treatable. Ask around to various detailing shops to see if they have an "Ionizer" that basically neutilizes the mold to a degree.
I know Advantage Ford had one when I worked there 4 years ago. But most detailing studios can do this for a flat fee. If you use chemicals, you can ruin the fabric. Best let them do it.
"The music business is a cruel and shallow money trench, a long plastic hallway where thieves and pimps run free, and good men die like dogs. There's also a negative side"