It's possible, yes - but it's going to be really, really difficult.
You'll need to start here: RedMon - Redirection Port Monitor
] (or find something similar) and then "decode" the printer output (as it isn't sent to the printer in the form of text) back into "English" you can save. Bear in mind that the output will be different for each printer type it's going to, and probably each version of the printer driver as well - so you may have to do a heck of a lot of different "decode" methods.
It's a lot of work - much, much easier to modify your application to save it when it prints (and less likely to destabilize your computer, as well).