I can't even do the dive cancel combo offline. But the pinwheel loop is very easy, the reason you have trouble doing it online, I'm assuming, is because it's a real player and you get nervous? If that's the case, just try and get that out of your mind and focus on execution, that's what i do.
Speaking of dive cancels, the only reason I have trouble doing it is the super jump cancel after the first dive cancel into the 5d.....how the hell do you pull it off?! 2 > 9 is giving me a normal jump cancel....