Denso alternator wiring

You can do that but fuse the new wire or there will be zero protection in case of a dead short in that circuit, blown diode, etc. you also need to tear the bulkhead connector apart and fix issues with it Read the MAD article

Catalog

Also, what year/ model is this? Some "later" years have an engine harness connector which the alternator charge wire and other stuff rus through and they can be troublesome