I have never had to replace a catylitic converter. But have removed exhaust components from the exhaust ports on the cylinder head all the way to the rear bumper. Depending on what you have to do , it could be a simple as a few bolts and maybe a hanger and an electrical connection for the o2 sensor.

If you have to weld it in, I would find somebody. If not, i'd be looking into doing it myself or finding a buddy to lend a hand.

Make and model?