Probably the best way to do this will be to add a Custom Folder and set the TargetLocation to be [ProgramMenuFolder][USERSFOLDER]. Then, on the command line run
msiexec /i mysetup USERSFOLDER=aTestFolder
The thing that we can't do very well is get this through the UI. The problem is that we evaluate and resolve the NEWPROPERTY1 (the default property for the folder path) before we go through the UI sequence. If you wanted to be a bit bold, you could modify the built .MSI after it's built to add or move the NEWPROPERTY1 evaluation custom action to after the custom dialog in the UI Sequence. That might work, and if it does, you can build a script to reun on PostBuild to automatically fix it.
I hope that helps a bit.