You want the alternator to feed directly to the battery through the shortest route (path of least resistance)... this is often through the hot side of the starter solenoid for convenience. A heavy wire (10 or 8 awg) straight to the battery post is better. You can then pickup the main hot to the fuse box at the starter solenoid or battery whichever is more convenient. Your voltmeter can be on any switched hot circuit. Better to keep the heavy alternator wire out of the drivers compartment if you odn't have to for an ammeter...

-Chris