[Printing-user-general] Print too high

I'm trying to use a Oki B4100 on my linux system (ubuntu 6.06). Because there
are no drivers for it, I use those for the B4200. (The printer does work with a
HP-driver, but the quality isn't as good then)
My printer is recognized and it prints, but I have 2 problems.

I always have to push on the //-button on my printer before printing starts,
don't know how to solve this.

Also (it's a bigger problem), al my prints are moved up. So at the bottom of
the page the marging is much bigger and at the top it's very small (sometimes
text is cut off). Because it's difficult to explain I will try to give an
example:

what it should be:            
 ----
|A  |
|B  |  <-paper
|C  | 
 ----

what it is
 ----
|B  |
|C  |
|   |
 ----

Is it possible to solve this? Maybe by changing something in the *.ppd-file?
(this is the original ppd:
http://belgium.oki.com/binaryData/6683/ok4200pcl.ppd.gz)