Seems this interface isnt well supported, but you could have a look at
DMX Control which looks like it does support your interface, and does claim to be theatre usable.
Or you could flog your interface on eBay and splash out on PCStage which does do cue stacks to perfection, several times over :-) Or Horizon or something, a tool with theatre attitude.
Most of the cheap / free tools are aimed at dance parties, and those that aren't seem to be tools of limited ambition, as in experimental visual basic two preset desks with dippy crossfades.
For the market it addresses, Freestyler seems flipping good.

See
this thread for some more info on Freestyler.
Update: Another thing you could do is that if you can find some lighting software that supports MIDI control you could use that software with any MIDI show controller package, and even run them both on the same PC by using a MIDI loopback device such as the MIDI OX thing. Probably the cheapest show controller is again PCStage, unless there is one out there that pays you to have it, in which case where do I sign up

Or you could download an eval/demo of Showman, SFX, SCS etc.