I can confirm this does work as I have done it today, 27/03/13
1. Open both tapped out and game guardian
2. On game guardian, make sure the search regions are on 'more regions'
3. Search current money/xp/donuts in game guardian and then use or make money/donuts/earn xp
4. Search the amount you have now
5. Keep repeating until you have between 1and 8 results
6. Change the results which are 4bytes to however much you want.
(For donuts I only got it down to 8 results so change the ones which are 4bytes to how many you want)
Money and xp have stayed the same for me when going off it and coming back on, but donuts have reverted back down to 1..
Completed on Samsung Galaxy S3
Hope this helps