For MPC8358 custom board bring up, you need to modify initialization file PowerPC_EABI_Support\Initialization_Files\PQ2\8360MDS_rev1_init.cfg based on your target board.
Please create a bareboard project for MPC8358 in CodeWarrior IDE, in "Select processor and board" panel, please select processor PowerPC 8358 and board 8360MDS(rev1).
Then modify initialization file in CodeWarrior IDE from Edit->Debug Version Settings->Debugger->EPPC Debugger Settings->Use Target Initialization File.