i'll tell u the old ways u could get GP.
You'd haveto take note of ur current EXP, then goto mhs/ce once attached to engine.exe and search that value, then go play a quick game and gain some exp and and then search your new value and modify and lock it to a high number "1370000" was a value u could set as and you could gain 7,500 GP every matched you played. and u got massive amounts of EXP so you could buy any locked ranked gear from the shop
but it was patched.
another way was goto the shop and look at your GP, Goto MHS/CE and search ur GP value (ie,if u got 15,500 remove the , and just type 15500) and then go backto the shop and buy a scope and then take note of your new GP value and take it backto mhs/ce and search for the new value and then lock it at 999999 and u would have unlimited GP.
But both of them methods are patched. but u get the idea how mhs/ce is used.