This is basically what I've been doing to PL all my toons...

-70 Pally boost 4x toons 8lvls
-4x toon (8 lvls higer) boost 1xtoon (8 lvls lower) up to equal level. The Lowbie toon is used as the main and tags the mobs ungrouped while the 4xtoons stomp the mobs ass. Lowbie regroups (basically the Slavepens method at a lower lvl)
-Once the last lowbie is = lvl again go back to the 70 pally and do it all over again.

An example of wtf I'm talking about...

-Team of 5x hits lvl 15 through quests
-70 Boosts 4x lvl 15 thru DM to lvl 20
-4xlvl 20's boost last lvl 15 to 20 in DM using upgroup/tag method
-70 Boosts 4x lvl 20 thru Stock to 26
-4x lvl 25's boost last lvl 20 to 26
-70 Boosts 4x lvl 26 thru SM to 34
-4x lvl 34 boost lvl 26 to lvl 34 in SM gy/lib
-etc...

Note: For the ungroup/tag/kill/regroup method to work the mobs must be no higher than orange to your lowbie and no lower than green to your highbie.

You can also just use your 4x highbies to help your lowbie to quest however it is simplier to just do the same instance as they are being PL'ed thru in my mind so you're not running all over the world. Also you can kill (assuming you can find some post 2.3) outdoor world elites using the ungroup/tag killing method but they for some reason give less xp per kill than elites in instances of an equal level.

Also, YES THIS IS BORING AS HELL!!! But it is rather quick imo.