Take a look at Foundation Tools Foundation (DTF) for WIX. There is a DTF.chm file with a WIX installation with lots of information.
Assuming the installation process is similar to
( )
- SetupRegistration
- DoRegistration
SetupRegistration , , . ProgID , CustomActionData "DoRegistration" (, )
DoRegistration - InstallExecuteSequence, , InstallFiles, . Session.CustomActionData ProgID, , .