Hi David,
The goal is "Length" = millimeters, "Mass" = Kilogram, "Force" = Kilogram-Force, "Time" = Seconds, "Temperature" = Celisus
Unfortunately, this is not possible due to the definitions of the various physical quantities. You have to have "consistent units" - here are a couple of the top hits from Googling that:
http://www.dynasupport.com/howtos/general/consistent-units
http://femci.gsfc.nasa.gov/units/
Basically, you only need to define three of the key units (plus temperature), and the remainder will all be derived from those. Typically those three 'base units' can be mass-length-time or force-length-time.
For example, standard SI units are mass-length-time (kg-metre-second), and force is a derived unit of 1 N = 1 kg.m/s^2 (mass × acceleration). If you choose other base units, such as millimetres, then the derived units change accordingly.
If it's any help, I prefer to use Mechanica in N-mm-s, so that stress is directly in MPa (N/mm^2). I then have to remember that masses are in tonnes (1 N = 1 t.mm/s^2) and torques are in N.mm, but I find these quantities relatively easy to work with.
I think that Creo has some improvements over Wildfire versions in handling different units, and possibly allowing selection of different units in the results window - but I agree that this doesn't help with the output in the run summary file.