I guess it would depend on the .NET user control you are creating.
http://go.microsoft.com/?linkid=2316315
This webcast shows examples where no cab file were used, but since you are using COM interop (you are using .NET) the MSI is necessary.
As i read it, you create a Setup Project (add project > setup and deployment projects) then add a CAB Project (under Setup and Deployment projects).
Add the INF file mentioned to your Setup Project. Chance MSI file name to match your project.
Be sure to set the Content property for this file, or it wont be included in the CAB project.
You now need to add output from your project to the setup projects:
Right click setup project and select Add > Project Output
Select your UC project and select Primary output and Content Files (hold down ctrl), press OK.
Do the same for the CAB project, but remember to select the setup project instead of the UC project.
Primary output is your dll's, content files is your User Control, INF files etc
When you build your solution, the cab file will be in the bin directory of the setup project.
I havent tried the above, but it should work
HTH
//AndersR