Pretty simple
I have never seen a 290 of take this with a grain of salt.The alternator will have a + terminal and maybe a - terminal. The terminals will be on the side opposite the pulley and will be the "big" bolt and nut. There should be some sort of symbol cast into the body to indicate the terminal. All you have to do is run the + to the "common" terminal of your battery switch and the negative (if there is one) to the battery - terminals. If the alternator does not have a - terminal then it is "grounded" to the engine and there should be a large (as large as the + wire) attached to the engine block and running to the battery - terminals. It is usually attached to one of the transmission to engine bolts.That's it. + to + and - to -Caution. a 12 gage wire will not carry 50 amps without frying so size your wiring to look like your starter + wire.A simpler solution is to attach the + terminal to the + terminal of the starter solenoid. The solenoid is already connected to the battery switch so you can use the wire to pull double duty.