pierre
Ive found that you can use a small portable light box to "backlight" a slide or negative and just use the normal reflective setting on a flatbed scanner (same one youd use for scanning a picture torn out of a magazine or what not). I have an Epson 3170 and it only accomodates up to medium format negs/slides so I use a small 5x7" light box to back light my 4x5 negs under a loose sheet of 8x10 glass. works pretty well Ive found.

in regards to contact printing. I am somewhat of a grommet to largeformat shooting. but Ive managed to go through hundreds of 4x5 sheets of film in the 6 months since I got my Crown Graphic and moved onto my cambo. Ive enlarged alot of them and been pleased with the resulting 8x10. But like all are saying.... I feel something different with the few I have contact printed. The image seems honest and true to form. thats what I saw thats how I envisioned it with all its proper (or improper) exposure/composition etc etc.
I am yearning for an 8x10 to be honest.
4x5 seems to be a stepping stone to where I would like to eventually be.