Sorry but I haven't had a chance to work with that kind of printer in years so I don't really know. (But I wanted to let you know that at least someone had looked at your question.)
You might look at the PrintDocument object's PrinterSettings property. Or its QueryPageSettings event. In theory, you can print each page with different settings, although I haven't tried changing the page lengths.
Sorry I can't be more help. If you figure it out, post the solution here.