I sure hope ‘duped’ is too strong a word… Yes: TWAIN compliant implies a TWAIN driver, which must be provided by the device vendor. Save that brochure! Actually, they still have a PDF on the net that lists the Lexmark X632s as “TWAIN compliant” http://www.lexmark.com/US/cms/products/X632s_Spec_Sheet.pdf
But if there’s no driver on the CD, there’s certainly no driver in the downloads & drivers section – Maybe they just forgot to post it. The good news is – I’ll bet my socks that’s a Visioneer or Avision scanner on top, so there *should* be a TWAIN driver somewhere… Have you tried hassling Lexmark tech support?