Hi TheJord - I suggest you contact members Dogbert, Sete, Ranofer. They have all shown an interest in this sort of stuff. Dogbert has already alot of material already setup - probably not half slips though. He may be able to help and has volunteered to offer his support.
Promo cards to support the league would be fantastic, and would generate interest (hopefully), but they only support the collector and those that play using real cards. It would be great to see promo cards produced that are supported by GCCG, Zorbec's, etc.
I would love to tackle the copyright issues and for the proposed PC to be able to produce full image v-cards if at all possible.