Extract the MSI file from exe (launch the EXE and copy the MSI with the cryptic filename from %TEMP%).
Created response transform, selected defaults.
Edited MST file:
ALLUSERS=1 (instead of 2)
Added xmlspy.lic file to \Program Files\Altova\XMLSpy2006
*How to get the xmlspy.lic file*
-Click on "ENTER a New Key Code"
-Enter Key-Code info and click OK
-Thank you: Click OK
-Click Save (this creates xmlspy.lic in C:\Program Files\Altova\XMLSpy2006)
-Click Cancel on pop-up Ad
-Copy xmlspy.lic in C:\Program Files\Altova\XMLSpy2006
Gotcha: XMLSPY creates its file associations upon first launch, Power users and Limited users cannot write those associations to the registry. Try to capture those changes and add them into the MST file.