http://www.sketchucation.com/forums/scf/viewtopic.php?f=20&t=723
this could help you... there is a part 2 as well and I'm working on part 3.
my local reproduction shop Springfield Blue Print sends me .tiff files those can be dropped directly into SU.
although I find it quicker to import into Autocad and trace there, it's more fun in SU.
good luck if you need anything let us know.