You need to set up a device node entry for the printer. Use the following command:
mknod /dev/usb/lp0 c 180 0
Different printer tools are installed with various different rights, and this may affect the access priviledges that you need with the device entry. It is normally correct to make /dev/usb/lp0 rights the same as /dev/lp0, using the chmod, chown and chgrp commands.
You should now be able to use this device in a normal /etc/printcap entry. I recommend use of automated tools to generate such files, such as RedHat's control panel print-tool.I find this driver to be pretty good, although perhaps a bit slow.
If this does not appear to work, check that you have actually loaded the module, and double-check the /etc/printcap entry - especially that the device file matches the one you just created.