ealbers writes:

Is this a job I could do myself? Just solder to the existing pipes
and wire it up to the 240?

Brazing, not soldering. Requires a purge gas inside the lines to avoid
oxidation.

You can get the EPA certification at http://epatest.com/, then buy about
$1K worth of vacuum pump, gage set, R-22, and other tooling to fill it
yourself.

Potential for foul-up of the first try is large. I do it myself and it is
well worth it to maintain the many A/C systems in my purview. It takes a
significant investment and study, but then you'll make it up on the first
big job like this considering what the contractors try to charge you.