SIP is finicky. The stars gotta align just right for it to work easily. Temperature if pretty important for SIP; it doesn't like colder temps. RyDawg gave me some pointers on successfully using SIP, and they really helped (huge thanks to the 'dawg for these tips)...
1. Temperature... gotta be warm.
2. Paint... must be *completely* free of *any* residues. Do a very thorough IPA wipedown before hand.
3. Application.... start with a very small amount. It helps if you prime the pad first. Apply a bunch of SIP to the pad, and very thoroughly work it into the surface of the pad, then wipe the pad down with a MF. Apply a couple pea sized dots to the pad, and begin polishing.
4. Stop polishing at the first sign of the polish drying up. The first application might give you a very short working time. Stop. Remove the residue. Apply a couple more pea sized drops, then start again. For some reason, doing this process (stopping, removing residue, then starting again) will gradually increase the working time of SIP. After a couple times, you should get a really nice, long working time, giving you the ability to completely break it down.
5. Pad choice... For some reason, certain pads just don't play well with SIP. If you've followed the above steps, and are still having problems, change to a different style pad. Quite a few guys have had a hard time getting SIP to work well with LC Orange foam. I like to use SIP with purple foamed wool for heavy defect removal, or just a zero bite wave foam pad for medium/light polishing.
6. RPM's. SIP doesn't like a really fast speed. Shoot for around 1k rpm max.
7. Pad cleaning... wipe down the face of the pad between applications. If you're using some flavor of wool, spur the heck out of it between applications.
Let us know how it goes....
Edit: this is all assuming you're using it with a rotary. I never have had much luck using SIP with a DA.