Hi Tony,
Yes it was a pretty long distraction 
I have pasted the text below from our pdf_pen_table.pnt between the rows of stars.
You can see the comments relating to what pen does what. Also you can see the weights we ended up with. These are absolutely standard for the parts and dimensions but you can see that I used a very thin line for tangents (Pen 7 and this works well) plus I made a thick line for pen 8 which I did not end up using. The addition of the extra color infromation for each pen forces these to draw black but lets you put a colored shaded image into your drawing it that is what you want.
*************************************************
! This is a pen table file.
! use for PDF creation within ProE WF5 (Creo Elements/Pro) M100. Brent Drysdale 07Aug2012
! Pen 1 = white entities (object lines)
! Pen 2 = yellow entities (text, dimensions, cross hatching)
! Pen 3 = gray entities (hidden lines)
! Pen 4 = red entities (Highlight - Primary (Dark Red)Selected (Red)Secondary Selected (Orange) All items plot as solid lines:
! Spline surface grid (does not plot in drawings)
! Pen 5 = green entities (sheetmetal)
! Pen 6 = cyan entities (section)
! Pen 7 = dark gray entities (dimmed e.g. tangent edges)
! Pen 8 = blue entities (spline surface grid) [use for drawing perimeter border in format]
pen 1 thickness .035 cm; color 0.0 0.0 0.0
pen 2 thickness .018 cm; color 0.0 0.0 0.0
pen 3 thickness .018 cm; color 0.0 0.0 0.0
pen 4 thickness .050 cm; color 0.0 0.0 0.0
pen 5 thickness .035 cm; color 0.0 0.0 0.0
pen 6 thickness .018 cm; color 0.0 0.0 0.0
pen 7 thickness .008 cm; color 0.0 0.0 0.0
pen 8 thickness .050 cm; color 0.0 0.0 0.0
******************************************************
And there is more info such as a spreadsheet I made from other collated infromation for the above values (searching the intergoogle)
I have also attached a testdrawing I recently made from within ProE WF5 (seems to work the same in Creo 2.0). It is A3 which is our most commonly used size. Works for us.
Regards, Brent