I mentioned this to The Mighty Gresh on twitter - I started dual-boxing again (so I could power-level my rogue to 60 using Recruit-a-Friend [so I could pickpocket junkboxes for Insane in the Membrane]). I'll actually be leveling two or three alts this way - since Lasombre (the rogue) is already 18, I needed a quick way to boost Sigrat (the paladin) up to join her. And so, I started a relay race, only using a dwarf instead of a baton: this involved creating Bubblesqueak (the mage) to lead Sigrat around and have him kill stuff until they hit 18, then passing Sigrat off to Lasombre... but wait, you say, you put the mage in the lead? There's a method to my madness:
I wanted to make sure I could get Sigrat's keybindings set up ahead of time, and
It's easier to pull with a mage, on account of having a ranged attaack with a range of greater than 10 feet, and
There have recently been changes that made dual-boxing a melee character ... well, possible.
It's still a touch awkward (namely if you try to attack with the melee character while the monster is still running towards you), but it's a far sight better than having to run through the mob and flip it around. Here's the guide. (Thanks to the folks at Dual-Boxing.com for figuring this out well before I ever needed it.)
Besides the required keystroke passing app (I use Keyclone), you'll want to have an addon that allows auto-following after combat. I'm currently using Jamba, last time I used TwoBoxToolkit. I can vouch for both; though Jamba's got features above and beyond TBTK, and makes configuration a lot easier (plus has some graphical niceties like a small window on my "master" character showing how close everyone on my Jamba Team list is to leveling, whether they're following, etc.), TBTK will get the job done.
On the character or characters who will just be following you around, turn ON click-to-move (Main Menu > Interface > Mouse > check Click to Move).
On the same character(s), go into the key bindings and bind something to Interact With Target. As the name implies, this is essentially a keybinding for right clicking. I set mine to the same key that, on all my other characters, makes pets attack. It's fitting. :)
And last but not least, you'll want a macro you can hit to make this character assist your "master" character. I use a simple macro that says "/assist party1" because my dwarfadin will actually be following two different people. For ease of use I actually worked this into my other macros - I macroed together "/assist party1" and Judgement of Light, for instance.
On the "master" character, combat goes like so:
Engage target. For ranged classes, pull, for other classes, wade into combat.
Once the target's positioned, hit the keybinding that corresponds to the assist macro on the follower, then the keybinding that corresponds to the Interact With Target keybinding on the follower.
Because of the way that assist, click-to-move and the Interact with Target keybinding work, your follower will target your target, then "right-click" it - i.e., pull out their weapon and run into melee. This way you're not strictly limited to having a ranged follower or healbot follower for ease of use. I was actually considering having him level up holy and using my rogue to do all the damage, but it's just more fun this way.