I know this post is a couple months old, but I have a few comments I'd like to make about multiboxing in FFXI to the benefit of anyone(else) who might happen upon this post(it's the first finding in Google for IS/FFXI)

Innerspace doesn't work due, mostly, to POL. So we can add that to the list of it's other atrocities. Fortunately, you don't need IS to box in FFXI and FFXI is actually very multibox friendly... out of the box, so to speak-- with one addition. Windower.

If you use Windower( http://windower.net ), instances of FFXI will switch control instantly, rather than have a few second delay as is normal without windower. And, more importantly, you'll be able to use a plugin for Windower called Multisend (http://forums.windower.net/topic/15086-multisend/ ) .

(The post editor wouldn't stop underling from the link)

..., which allows you to send in-game marcros from one window to all other windows. This, combined with a robust auto-follow and built-in auto-face, auto-loot and... 'auto-maintain-melee-range-while-auto-follow-is-on' make FFXI one of the easiest games to multibox.

Plus, the level-sync system opens up interesting possibilities. Theoretically, you could level 1-75-- 99 in any zone you want, as long as you have one class in that level range.