I'm afraid that won't work. DOSBox does not natively support printing and it has no knowledge of external devices. There are builds with printing enabled, but those would still require mapping the printer in Windows.

Would it be possible to make DOSBox just print to an image format? Like a PCX, BMP, or TGA or something? Maybe even PNG. Similar to how a fax plugin a long time ago that I had would fax things to image files instead of actually faxing them.

There's a patch to do that but it's not included in DOSBox itself.

Gulikoza's
http://www.si-gamer.net/gulikoza/dosbox.html

or HAL9000's builds might have print to .PNG support. Can't remember.

Cool!

Also, I was incorrect earlier. I had a printer driver that would act as a fax machine and save the printed document as a BMP (I think it was) and dial a phone number via your modem and the recipient would receive it as a fax from their fax machine.