Hi and hello! Wow! What a classy thing to do.
If you're using the original visual art of him, I'd have to get in contact with my graphic design guy.
If you're just using the character himself, I'm more than amenable to that. Just be sure to include in the credits:
The character of Jurgen is originally sourced from EVERY GOD WILL FALL by Sasha De'ath and The Eldritch Tomb. He is used with full permission.