Ah, yeah, you'd just need to scan whatever doujinshi you have. I'd give you encyclopedia access, so you could add more to that linked doujinshi page. If you don't own a copy, you can always make a listing still, just without a link. (And if you do own it and scan it, just send me a .rar and I'll upload it to the Compendium.)
So it just comes down to having some free time, encyclopedia access, and a willingness to scan your collection.