Since the scanner and the driver are on the clientside, there won't be a whole lot you can do via ColdFusion (since it's serverside... if you tried connecting to a scanner object with ColdFusion, it'd probably try to connect to something hanging off the server, which isn't what you'd want).
There's a chance you might be able to do something with ActiveX... or find an ActiveX control already that'll allow you to do it.
The one thing you have going for you is most scanners can utilize TWAIN drivers... so there's a better chance that they're standardized enough to where, if someone's written a TWAIN ActiveX control, it just might work for all your clients/users. Hope it helps,
-Carl