Is it possible to write a C# assembly which when loaded will inject a method into a class from another assembly? If yes, will the injected method be available from languages using DLR, like IronPython?

namespace IronPython.Runtime
{
    public class Bytes : IList<byte>, ICodeFormattable, IExpressionSerializable
    {
        internal byte[] _bytes;

        //I WANT TO INJECT THIS METHOD
        public byte[] getbytes()
        {
            return _bytes;
        }
    }
}

I need that method, and I would like to avoid recompiling IronPython if possible.