Luckily, FTL does not need to be arbitrarily limited. The real limitation of FTL (as far as ISBoxer is concerned) is that you need a separate macro per Character, per Character (meaning that each of them needs a macro capable of following or assisting any other given character) -- not that they have to be on the same key. Having them on the same key is a shortcut.

WARNING: The rest of this is ADVANCED.

So... for anyone who WANTS to go beyond the natural limitations of the built-in system.... read on. But make sure you're sitting down, and have lots of coffee or something. Prepare to be confused, you have been warned. Anyone else, I highly recommend you just stop reading now before you start thinking that this is some necessary part of ISBoxer that you need to learn in order to be successful. It's not and you don't.

I described how an FTL-like system can be implemented for pretty much any game as of ISBoxer 35 in this post: http://isboxer.com/forum/viewtopic.php?f=14&t=233. Then Creo, a LOTRO player, took it to heart and implemented it for his LOTRO configuration. In the same way, this can be done for WoW instead of using the built-in FTL implementation, in order to reach more than the number of possible combinations on a single macro.

So first you need a set of macros with /assist for every single character (Same for /follow if you want /follow to work). Then you need a master Assist mapped key with a hotkey for manual assist (I'll call it "Manual Assist"), an Assist mapped key without a hotkey for a Do Mapped Key Action to do (e.g. from the master or from an FTL DPS Key, etc; I'll call it "Assist Leader"). The Manual Assist, or the FTL DPS Keys, will simply Do Mapped Key to do "Assist Leader", which will be virtualized depending on who's "leader" at the time so it does not need to do anything at all. You can put a Popup Text Action in it to warn yourself if your system is not working.

Assuming you're using multiple PCs the most reliable method of virtualizing the Mapped Key is probably going to be to build it into the mapped key(s) you're manually hitting (as opposed to when you switch active windows). So you'd have something like the "Slot ### is leader" mapped keys from Ualaa's guide, but it'd be by Character rather than Slot, then you'd have a master "I am leader" mapped key. For each Character, you would virtualize "I am leader" as the Character-specific leader mapped key (e.g. "character XXX is leader"). This is done by selecting the Character in the top pane and "Virtual Mapped Keys" in the bottom left pane, then on the right you can make it read "I am leader" is now "character XXX is leader". That way, before your auto-assist you use a Do Mapped Key Action that does "I am leader" in the CURRENT WINDOW, and regardless of which character you're playing they will interpret it as their own "character XXX is leader".

Now... for each "character XXX is leader" Mapped Key, you put in a Mapped Key Virtualization Action. The "Assist Leader" mapped key I described above needs to be virtualized as this Character's /assist mapped key. Same can be done for /follow ("Follow Leader").

As far as the actual /assist <char> mapped keys, you can create a few WoW Macros similar to the FTL macro, using [mod:whatever] to have up to N combinations on a single hotkey, and then use a Keystroke Action to send the keystroke instead of duplicating the WoW Macro 40 times in your configuration. Just put the WoW Macros in a Mapped Key that will never be used, in a Key Map that is active (e.g. the Control key map, don't put a Hotkey on the Mapped Key, and you can put all your WoW Macros in the same Step of this Mapped Key. its only purpose is to hold/create the macros)

It's a simple concept (interpret X as Y), but kind of a complex use of it, and somewhat time consuming to set up. All that's happening is you're telling "Assist Leader" to translate to a different Mapped Key depending on which guy you're pressing buttons on.

I'd be happy to help someone through this as needed