Having issues installing Powershell 3 on POSREADY 7

I have been trying to install Powershell 3 on POSREADY 7 for a few days now, and I can't seem to get it.  Powershell 2 is already on the box (out of the box).  I ran windows updates - all relevant updates are installed.  I then followed a number of different "how-to's" on installing. I first installed .net framework 4 full.  And then Windows Management Framework 3.0.  

Everything says that after installing windows management framework it should prompt me for a reboot, but it does not.  I reboot regardless, start powershell and $psversiontable still gives me 2.0.

Is it possible to install 3.0 on POSREADY 7?

Thanks in advance

sb