If i remember correctly you can excite a Ford alternator externally to get it going. You're looking for 13.8 to 14.2 volts for a good charging system.  You could scrap the whole deal and get self exciting alternator that will operate independantly of any other system and wire to the battery directly.

Jimmy's right throw the one-wire job on it.

Can I add a second cable from the alt direct to the battery.  Isn't there a fuse link between the two.  I need to know step by step instructions and hardware.

I agree wholeheartedly, rip all that crap out and go buy a 1-wire.  I sell one at work, they're pretty common and not any more expensive than most older style V8 alternators.  You literally bolt it on, and run a wire back to the shutoff switch.

One wire alternators are available from a variety of vendors and probably your local alternator rebuilders. Single wire is a single wire to the charging circuit leading to the battery. There are two ways this can happen; one direct to battery (+) and one with a toggle switch in between the alternator and battery + post.

An on / off toggle is required in most applications because of the field supply design in modern alternators which if not disconnected will drain the battery when parked and the engine is off (drain times vary, from 2 to 24 hours).

Japanese (Denso is one example) Alternators are not true 1 wire designs in that they require a jumper in order to work, but are still connected with a "single" wire from the main alternator + lead to the toggle switch and onto the + pole of the battery.

I agree with everyone else, junk the stock alternator / charging system and go one wire for recharging and maintaining electrical power to the battery. That said, I also agree with Doug109, caution must be exercised with Ford ECM's for the engine to run - without the proper circuits still functioning, the ECM mail fail or go into limp mode causing the engine error codes that don't exist - such as the "field" wire which connects to the dash gauge / warning light. if memory serves, when the ECM detects reduced electrical power or warning, it may reduce power to the coil packs. Doug109 probably has more knowledge in this area than I do.

I know in my 2004 Ford Expedition, when my alternator failed, it died in quick fashion and drained battery power in 50 miles...