Have you tried just scanning them? I've scanned a few back in June and they came out OK. I don't remember if I had to reverse the image though. You can see them on my Flickr page.
"Getting Started in Wetplate Collodion Photography" article
"Construction of a Square Bellows for a Wetplate Camera" article
on Tumblr.com & Flickr
Model Mayhem Profile
My APUG Gallery