Matt Laur , Jun 25, 2009; 10:28 a.m.
First, you might need a very large flatbed scanner, or the patience and skill to carefully scan sections of the work at a time, and stitch them together in post production.
Second, the scanner's light source travels with the sensor. It can do some very odd things when it encounters the 3D texture of the oil paint. Alas, a carefully lit photograph generally looks better - even without regard to the fit-it-on-the-scanner isssue.