If you are budget minded you need to use Printer Device Type *AFPDS. Assuming that Lexmark 2491 supports *AFPDS. A quick call to IBM will resolve the issue. Ask for latest AFPDS driver. Make sure you uninstall Client Access printer support. It will conflict with AFPDS driver from IBM.
We use PC forms print via AFPDS here and I have detailed documentation if you need additional help.
Good luck – John