Connect your charge wire (6ga is what I use) to the lug on the starter solenoid.

It will share this 1ga cable to the battery with no problem.

The manufacturer of the 100amp alternator suggests you connect to the battery because of a probable limitation in stock wiring. Since you have better-than-stock wiring, it should not be an issue.

Remember to tap the gas to get the charging system running after you start the car (bad habit of one-wire alternators).