The SCRIPT_ADDRESS stands for the P2SH addresses, those that start with 3. If you notice it, it has “5” in the decimal version:
base58Prefixes[SCRIPT_ADDRESS] = std::vector<unsigned char>(1,5);
And by going to the page I've linked it you can see the decimal prefixes and their leading symbols:
Change it to whatever you want. Same goes for SECRET_KEY & PUBKEY_ADDRESS.