Not familiar with that specific machine but In rasterlink in the quality settings cant you change the overprint to 2,3 etc to essentially give it a double hit?
I could be talking nonsense though.
No thanks for that i did try it. Problem is when i am using other colours they all overprint twice so double hit on the cmyk as well, and running colours at 50% had them looking washed out even with the double hit.
On top of that the white didnt trap properly and still looked opaque.
For anybody looking i found a work around.
Set up 2 special plates (white) composite them both to print bottom, valid pixel, set up the parts you want to print white in your design as an ugly cmyk colour you will never have in your cmyk list and replace this colour to 100% white 10% yellow.
Works great.