While in gameplay, hold the L trigger, then press the Y and A buttons at the same time to access the cheat menu. You can keep hitting accept to get more and more of the cheat.

10 constitution points - N STINE
10 dexterity points - ZXE053
10,000 EXP - DSP633
500,000 gold - KNE637
Invincibility - PELOR
Will Potions(Large)(10 each)- GEE
Healing Potions(Large)(10 Each)- Thompson
Tomes of the Teacher - MEFFORD(10 each)
Unlimited MW - OBADHAI