I think ESRI may be wrong on how to properly set up a custom installer for your custom dll’s for ArcMap etc.
It’s basically implying that you should use:
Which translates to soemthing like “C:\Program Files(x86)\MyCompany\bin\foo.dll”
But this may not always be true, what happens when your user wants to install to a custom installation directory? The ESRIRegAsm.exe tool will always fire against – C:\Program Files(x86)\MyCompany\bin\foo.dll, and not where the user selected to install! – it’s basically hard wired so that means your customers could have problems trying to install your software. It’s better to use:
Which is basically the value you get back from this stage in the installation process (although it’s not very clear as you don’t see that as a variable in the properties window for this stage!):
This will then run ESRIRegAsm.exe against where the user decided to install your dll’s, properly installing the dlls into ArcMap etc. This is, I believe more foolproof. However if I have got this wrong, I’m happy to be proved wrong 🙂