How to register a legacy typelib (.tlb) on Windows 7?

There is also C:\WINDOWS\REGTLIB.EXE that seems to be part of a standard Windows 7 installation.

It comes with .Net framework installation. On my machine I found it as:

C:\WINDOWS\Microsoft.NET\Framework\v4.0.30319\regtlibv12.exe
C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\regtlibv12.exe

Well, I guess I can answer my own question (and for anyone else who has the same problem):

Apparently, regtlibv12.exe is part of Visual Studio 2010 (contrary to what I read on various Microsoft forums), but it is located in the Windows\Microsoft.NET\Framework\v4.0.30139 folder (not the v2.0.50727 folder). Using that executable I was able to successfully register the legacy typelib (.tlb).