tlbimp is used to import the COM type library content into a meta data file (DLL) that can be used by C# or any other .net language platform.
tlbimp <name of any file contains COM type library> [options]
There are couple of options in which you use mostly are
1. /out:filename - to hold the meta data information and this will be used by other .net applications such as C#.
2. /keyfile:filename - This is used for signing the assembly with strong name. You can create this file using sn utility "sn -k test.snk"
3. /namespace:namespace name - You can specify the namespace that will be applied to the type library. By default it will be filename specifid in /out parameter
For the complete list of options, visit at http://msdn.microsoft.com/en-us/library/tt0cf3sx(v=vs.80).aspx