How to assign a Project Type (Work Area Type) to an existing Work Area?

Our system has ALIM connector creating the Work Area Folders in ProjectWise, all processing in PowerShell is to Work Area's that already exist.

I use GET-PWRichProjectTypes to get the list of all work area types that I can apply, and once the Work area type is applied to the Work Area (manually currently) then the properties can be updated UPDATE-PWRichProjectProperties, but I can't find a cmdlet to set Work Area Folder. 

Thanks

Ray