We are just using SMSInstaller and batch files to do the job. As regsvr32 is builting, why should I not use it. Well, you didn't say that in your first post, you said you were packaging it. As such, using RegSvr32 is the lazy way to register DLLs and OCXs. As I said, if those files have dependencies on other files which are missing on the target, registration will fail.
The if I need uninstalling the ocx, how would I prevent a conflict? You can't control reference-counting using SMS and dumb batch files. If that's your chosen method, you're going to have to build a monumental script to do what an MSI (which SMS can handle) and the Windows Installer engine will do for you out of the box. If you add up the time you've spent posting and reading responses, you could have built such an MSI. :)
EDIT:
IIRC, Wise makes available for download a merge module containing this OCX. If not, you can convert the MSI you're going to build to a MM and use it for other apps which require it. End of conflict.