Well, I looked at the popbaloon source and the timer stuff makes perfect sense

The only thing I still am unsure of: to adjust the target FPS, would you adjust the variable OneMSec, as this would appear to affect all movement?

If, in my existing code I had values already, such as x:=x+2 which now should be x:=x+(2*UpdateSpeed) or so, If I wanted to retain my original FPS target of 60FPS which I was getting with the VBLANK, how is the OneMSec / UpdateSpeed adjustable for this?