Printing Transparency using i-plot?

Hello,

 

I am trying to print transparent filled shapes using i-plot by using the .pen file to control it. Does anybody have a script or know how i can do this?

# colors 101-163 to transparency
if (color .in. 101-163) then
 transparency = 80
 priority = 5
 endif

Above is what I have in my .pen file and it's still not printing transparent. Any help would be much appreciated.

Thanks