Force NCover 1.5.8 to use v4 framework like testdriven.net does?

Question

I want to run coverage from the command line, but can't seem to get NCover 1.5.8 to instrument the code. It must be possible as when I run coverage tests with TestDriven.net it works. the difference seems to be that TD.NET is able to get NCover to use framework 4.0 (you get this in the log when it runs : MESSAGE: v4.0.30319) but from the command line I can't make it (I get this in the log : MESSAGE: v2.0.50727)

So how can I make NCover play nice with nunit from the commandline, like it does with TD.NET?