NT and 2000 come with print services for UNIX, although it is called something else in NT. Microsoft TCP/IP printing I think, no sure. With this installed (not installed by default) you can print to an LPR port.
lpr -S <IP adress> -P <queue name> myfile.pcl
For Win9x you would have to download a LPR port like ACITS which has command line lpr.
If you are printing IPP to 631 or hpnp to 9100, I'm not sure what you would do.
Good luck and have fun,