Well I just did this as well as removed the PS system...
I just used a screwdriver on the schrader valve to uh, vent the refrigerant into my, uh, Ghostbusters vacuum!
I messed up the A/C lines since it was freakin cold out and just used the fittings on them to plug the holes going through the firewall by cutting a circle of tupperware and putting it in unions.
Very nice write up!