Self-modifying C# (MSIL) code?

Question

How can I dynamically modify MSIL code in-memory with C#/.NET?

And yes, I'm really looking to replace existing code that's already in memory on the fly.
Specifically, I'm not:

• Looking to only generate new code (via expression templates, ILGenerator, etc.)
• Trying to emit a new binary module in the hopes of loading it into memory later

Answer 1

.Net Profiling API seems promising.

Otherwise, I'm stumped.