Hi,
Ok, I understand. If your pattern is linear, choose MODIFY->VALUE-> click on the second extrusion of the pattern, PRO/E will give you the dimension between the second and the first extrusion (the pattern increment).
If you want to create a dimension between any 2 pins in your pattern, then create a feature analysis and create a parameter to measure the distance between the two protusions you desire. This parameter, let's call it "distance" can be evaluated or used in other relations by the following:
distance:FID_analysis,
where analysis is the analysis feature you created.
Hope this is what to expect.
-Hora.