Hmmmm - I am not so sure the ship has sailed yet.

If you are 100% positive that the crankshaft hasn't moved, and neither of the camshafts moved when the belt released, then there still is hope.
Remember we are talking about a toothed belt here, so if you very carefully turn the crankshaft XXnumber of teeth to line up the marks, and then turn each camshaft the same XX number of teeth, you still should be correct.
If you go this route I would remove all the spark plugs so that you are not fighting compression as you turn the crankshaft. You will still be fighting the valve springs as you turn the camshafts, but that is easier.
I know that I wrote down the number of teeth on the belt to go crank mark - left cam mark - right cam mark, but I threw it away when I was finished.
Perhaps someone more diligent than me still has that info??

PK