From my perspective, I've been using a level 80 mage outside group to help PL my group for the past few weeks. Without any real changes to ini's or anything, other than triggered percent to cast nukes, I simply do this:
Start up EQBCS, then my group, get all macros loaded and going on each one. While they're buffing the ever living snot out of each other I have the mage loaded but sitting nearby idle.
Once everyone is doing their startup routine I switch to the mage, and run:
/mac kissassist1004e15 assist pc MA 65
Edit: alternate method: /mac kissassist assist pc MA 65
Replace MA with your main assist's name of course. The trigger percent of 65 was chosen because of the order of spells I cast with the mage. By the time the pet assist and first spells have fired off the mob is below 50% health almost every single time. At this point she basically burns the mob to a pile of cinders.
Edit: You most likely want to lower this percentage to below 50 if you're PL'ing a lower level toon. I noticed that a lvl 50 mage PL'ing a lvl 2 wizzy gets the kills a bit too often because it takes the wizzy and her merc too long to get the mob from 65% to 49% before the mages kill nuke goes off, and especially as the pet rushes in at 65% too.
Remember that your group/single character only has to do a minimum of 51% damage to the mob to get full experience count for that mob. As long as the mage does less than 50% you only have to half kill every mob. the kissassist1004e15 is simply eqmule's variant of KA if you're wondering, it has a few additional bells/whistles and controls, but either KA command will work for this scenario.
Edit: I also discovered recently that not having an up to date copy of VV Kissassist can make for some rather odd effects. I started a new character with a lower level mage and cleric supporting out of group and no matter what I defined as the start percent and no matter whether mq2melee was on or off, my out of group characters would rush in and attack and send pets instantly upon beginning combat. This only occurred while running mule's variant. I switched to straight KA and the problem was resolved. So, knowing that, make sure you're mac's and programs are up to date, especially if you start getting odd reactions from your active macros.
Within my mages ini the only changes I made to her normal level 80 group spell lineup was to lower the percent trigger point to begin casting nukes for the mob below 50% health. She will auto-follow the MA and keep the DS's up on him.