MAKEMSI has a "ServiceInstall" command to install services and the "ServiceControl" command to start, stop and delete services during install or uninstall or both.
You may need to create a service to "script" a process or execute a non-service EXE, if so have a look at:
The services applet can be handy when playing around with services, however if you get any service issues during installation or uninstallation close it before trying "retry". The applet appears to be a bit buggy and locks out the registry (or some other required resource). I had this issue on WIN2000, on WinXP the problem doesn't seem to occur.
|Service Won't Install!|
|Service Won't Start!|
If you need to query or set the user's privledges then these links should get you started: