Manipulate .NET bytecode - JIT regeneration?

Is it possible to manipulate the bytecode of a 开发者_如何学编程(signed) .NET program at runtime? E.g. by forcing the JIT to re-evalutate the IL?

Yes, it's possible with the .net CLR profiling APIs. But it's not an easy task. For instance, you can have a look at this article:

• Write MSIL code on the fly with the profiling API.