SOOOOOOOO
First read this
http://iosgods.com/topic/11407-roller-coaster-tycoon-4-all-versions-hack/
If you have any more questions come back here.
SO FIRST YOU INSTALL THE GAME
Finish to tutorial in the game and then find a mission you need to complete.
Kill the game from multitask.
Then you install Filza from cydia.
Go into filza
Go to /var/mobile/library/preferences/
Find com.atari.mobile.rctride.plist
Hold on it and click more on the bottom and click open with text editor.
Hit the search button and search for the exact name of the mission.
You will see 3 different things
Reward= Cash you get from the mission (So remove all the numbers and put in however much you want)
Premium Reward= Tickets you get from the mission (So remove all the numbers and put in however much you want)
Xp Reward= Experience you get from the mission (So remove all the numbers and put in however much you want)
Then hit save and then go back to the game.
Go to missions and then see if it worked (if it did everything will be 99999 ect.)
If it doesn't, do this again but on a different mission.
Credit goes to Dickeddocks 2for making the DIY hack and for most of the steps provided