CChristopher:
Thank you for your question regarding InstallShield AdminStudio 3.5 and modem installation.
If you are looking to redistribute the modem software via MSI format, then the Repackager should be able to do that for you. You will probably have to use the Snapshot method in multiple steps to do the trick.
If that is not what you are looking for, then please describe the problem in more detail so I might better understand the issue.