I tried adding the female IEC to an existing cord - the kind that leave you a pigtail hanging out the back. I removed it and wouldn't do it again, at least not on a good piece of equipment. I think it looks cheap, and if you're leaving the old cord there for the final run to the PS, I'm not sure what you accomplish.
If you're going to do anything, install an IEC with good hookup wire to the PS, or replace the entire cord with a better one.
Finally, you can probably find a shop to do the work for you, but it will be expensive because of the labor involved. OTOH, compared to the cost of a good power cable, this charge will probably be nominal
