For people to understand better:
You find the value for the currency you want to fake hack using whichever cheat engine (iGG, Gameplayer, etc) set the currency you're using to 10,000,000 or whichever value you choose (atleast 1,000,000 tickets/coins are needed to full complete both the achievements) and than you go too either Cartman or Butters and you choose an item to purchase x15.
Doing this will remove the fake currency but will say something along the lines of "you don't have the nessecary amount of coins/tickets"
This is because the game pulls on internal values to decided if you have the proper amount of currency to deduct but will check the server to see if you ACTUALLY have enough currency based on your true amount that the server has stored. Meaning if you actually have enough currency to spend on whichever item you're buying x15 than you will actually purchase the item with your true currency, so find an item that's more than your actual currency before hacking to buy.
Keep fake buying whatever you like until you've spent 1,000,000 tickets/coins and you will fully earn both the achievements.
I apologize that it's still a terrible explanation, been going for 2 days straight