[selenium96]

I kept the s trap under the sink & drained into the liberty pump, also a 403. Out from the liberty pump thru the darkroom wall. Up toward the ceiling thru the checkvalve. The waste pipe is near the ceiling so I cut into it and spliced in a fitting with a couple of those large rubber "no-hub soil pipe couplings." The pipe from the liberty pump should go up and over the waste pipe and enter the waste pipe from above to prevent any water from the waste pipe from going back down toward the liberty pump.

The scary part is cutting into the waste pipe but the no-hub couplings (see images below) are pretty easy to work with.

Good luck.