I have had good results with midi sync, or using panning or click like lead ins, but this is a pretty good tutorial too. Should be applicable for people making mulitrack renders on other platforms as well.
Last week end, I spent about 4 hours trying to re-align the separate renders from one of my Disco Dust track ‘usabiktch’. Since you have no other option but to record all 4 tracks individually, you need to re-align them time wise so that they regroup to do that song you know so well…
In theory it sounds easy, in practice it’s a nightmare. Especially if you work on a track that’s a tiny little weird like this one. After 4 hours of going in circles, I was going nowhere.
via mustakl
This is one of the most important issues that make a MIDI interface a NECESSITY. You can record and always in sync, no matter how many passes.