Measurement Studio provides MergeModules in the Program Files\Common Files\Merge Modules folder for every assembly and all their requirements. The Merge Modules define dependencies on everything that they require underneath (such as Mesa). If you are using WindowsForms you should just have to tell InstallShield to use the MStudioWinForms.MSM and all the other MSMs in that directory will also be included as needed. This includes UICommon and Common. This is how it works in Visual Studio and Wise, which is what I have knowledge about.
Most of our MSMs do not install to the GAC by default, they install to the application directory. This is changable through a ModuleRetargetable Directory for each MSM and can be cahnged to the GAC if you wish.
I hope this helps.
Jeff
NI