ooooh that's tricky. technically it can be done, but usually not with very good results. i've read this somewhere before... you need to make sure the document is perfectly flat, no crinkles and is evenly lighted up (using a softbox or flash diffuser mabbe?). you can't really use a piece of glass to flatten the paper too cos it'll catch reflections off any light sources.
Using a film or digital camera to do the above task
requires proper lighting setup, a lens for close-up
work such as a Micro/Marco lens.
So when investing in photo equipment, do take
this into consideration else you will not be able
to do the job.
If you cannot afford to have studio lighting
equipment, use more powerful torch light
or florescent lighting and make the necessary
A piece of glass is essential to keep the document
flat and keep it free from dust. Just make sure that
it is very clean. Have a black board placed over
the lens to avoid the reflections from any light source.
A dc with abilities to do very close focusing is
more ideal for such task. It is better than trying
to add Close up filters (+4; +10 etc).