I tried 42000000 81000000 & 42010000 01000000 and neither work
04 is 80
05 is 81
so if you your codes was at 818FD8DC and you wanted it to be set to 5 you would use
058FD8DC 00000005
changing the Base Address with the 42______ codetype can only change it to a multiplication of 0x2000000
Is that the same for all code types? just add one to the second digit?
Yes, for the most of them it is :)