I just rack my cider into the keg (or beer- wine would be the same method as well just with no forced carbing at the end).
I added campden tablets at racking time and potassium metabisulfide in an effort to keep the cider from re-starting fermentation, and added some apple juice concentrate to make it sweet. After the juice concentrace, sulfites and cleared cider were in the [sanitized and freshly re-gasket'ed] keg, I put the lid on, connected the CO2 and hit it with 30psi for a few seconds. This helps seal the lid, and will allow for purging of O2. I pull the pressure release on the keg to purge all gas, then hit it with 30psi again and let it sit for a half hour to an hour. I release the pressure relief on the keg again and after this second cycle of gassing/purging, most of the O2 should be out of the headspace of the keg. I'll then disconnect the keg from the gas, and just let it sit and age. If you want to have bubbly cider, either add priming sugar and no sulfites for a dry cider, or add sulfites and use any force carbing method that you prefer.
Since it is a higher ABV batch anyway, and because I added the sulfites I had planned on just letting it sit in the keg for several months before drinking anyway. When it is time to serve, I'll add the gas again, crank it up to 3-5psi (my lines are 4' and my setup works well at this pressure- YMMV), connect to a picnic tap or SS shank/faucet draft system and serve.
