The ColorVision software worked quite well with my Epson 1270 with 3rd party ink (way different gamut than stock) as well as a stock 2200. This used a moderately cheap scanner with good results. (Microtek, I think I paid around $150 for it)

Nothing ever calibrated the scanner itself.

No, I don't understand how it worked.

All I know is that after calibrating the printer and the monitor, I could hold a test print up to the screen and they were a dead perfect match.