I got it. You need iGameGuardian for this (i bought it for iOS8). Not sure if it works with GameGem aswell. Just do one of this run challenges and collect a few coins and pause the game, search the value with iGG. There will be a lot of values found, go back to the game and press resume (wait 2 seconds before pressing or game might crash). Collect more coins and search the next value... do this until you have 2 or 3 values left. Then change these to whatever you want and you'll get the coins after the run. Also works with Diamonds - collect 1, search value, collect 2, search value, and so on. this one takes a few 'extended' runs