Well there a two possibilities to do this:
1.) First of all you can do a registry export on the source machine (where you have done the packgaging of the setup and the service is installed
and then you can directly import the reg File (see doc attached) in Adminstudio
2.) You can use the Function "Install NT Service" within the Setup Design --> Components in Installshield Manager (see also attached doc)
as you describe the service isn't installed only in HKLM\System\CurrentControlSet\Control\Services??
have you tried the search fuction in the registry on the source computer, to find the correct location of the service?
If a service (if the programmer does't care about the windows guidelines) isn't installed in the path above then it's quiet difficult cause you don't know how the programmer has do the call to the service, which means the software is bullshit (sorry for the hard words, but this often the case)
If you do a repackaging from the scratch its not shure, that the service will be installed correctly...
I woud prefer first solution there you have normally the whole data to put directly on the client while the setup runs
One example to illustrate this:
PDFCreator is one of the tools which is very tricky to do a repackaging... everything worked fine in AS and after i distributed the msi file on the target (via SW Distribution) the SW where installed but no virtual printer driver was created, after i stopped and restarted the printer spooler Service on the target machine (via a external Exe File) the printer was sucessfully added
