You have several ways to do it. We used two of them:

- OPOS (works with most hardware with the same API)
- Direct commands to the serial port (commands will differ if your customer changes his hardware)

Both need a little investment of your time. Here is a link to some samples for direct communication with a serial port:

http://www.levelextreme.com/wconnect/wc.dll?LevelExtreme~2,2,9336

The article talks about another device, but working with a customer display or a drawer is similar.

If you dig in UT messages and downloads, you'll find more informations.