I am looking to specify a custom default directory for a wix toolset generated msi, reason being the program/install doesn't require admin rights for anything except copying program files to the program files directory, and I am considering allowing installation to the roam-able directory.
the WIXUI_INSTALLDIR
is basically what I was looking for, once I figured what I was looking for:
https://stackoverflow.com/a/3302238/832705
For reference, the Wix v3 install target directory input dialog (wix documentation link) that uses the WIXUI_INSTALLDIR
default directory xml structure.