C# codeparser/checker

[Nico]

On our project we want to do as much auto code checking as possible. Are
there any good code checkers available where I can add my own rules ?

If not, is there a code parser in .NET (or anywhere else?)where I can parse
the code to CodeDOM or something else, so that I can write my own checking
procedures ?

This is for C# specifically.

FxCop checks compiled code and helps a lot, but I cannot check rules in
source code, or add my own rules.

Total .NET analyzer doesn't allow me to add my own rules.

Any suggestions ?