Holes at an angle in large plates?

I have a large ish job, the material size is apox 2000mm x 1200m, my problem is i need to put some large diameter holes into it, some of these holes will partly cut into some hard inserts.

I have an old Machine with a Heidenhain TNC 415B, the machine has a manual "Huron" Universal style head, this being the case I don't have the ability to tilt the work plane in the control unit, I do have access to most Q parameters.

Any ideas on how i can interpolate these holes?