Bah gotta love how if something is going good, everyone has to keep it to themselves and not let others in on the fun. I'll go out on a limb here... here is EXACTLY how smn burns are done.
First off you need a puller, preferably high lvl RDM, or a high lvl PLD or WHM (being that they have their own enhancing magic) If PLD or WHM, they need RDM as sub... for one spell and one spell only, phalanx. BLU main wont cut it, it would get ripped apart by 100 mobs beating on him. A 75 RDM lasts for about 30 seconds without phalanx up before taking a dirt nap. It should be obvious how to pull and link the mobs, but the RDM should kill off the mobs that he attacked, being the smns won't make any exp off of it, since a lvl 75 claimed it.
Ok now for holding hate... as the rdm is going down the tunnel gathering up mobs, have the rdm spam a few bar- spells from time to time to keep the mobs interested in him. Its another good bet to have the rdm stop from time to time to let the mobs that had lagged behind catch up a bit. Also be sure to recast phalanx BEFORE it drops, or the rdm might find himself quickly dead... composure is awesome for this since phalanx lasts 9 minutes then. When the rdm reaches where the smns are he MUST /heal. Doing this puts direct hate from the mobs onto the rdm. If the rdm does not /heal, the mobs will lose interest on the rdm on the first diamond dust and depop. /heal again after a few seconds and try to get up. Most likely the rdm will lag horribly and be stuck resting for a bit. Its usually a good idea to recast phalanx right before you /heal to give you a 9 minute window to get back up. If stuck just keep pressing the up (move forward) button until the rdm gets up. At this point, start spamming bar- spells again to build up hate. After a minute or so, you're ready to go.
If you're wanting more mobs and thus more exp, it's always a good idea to have 2 pullers. One rdm will be the main tank and the other is a backup. The two go on seperate pulling runs, one on the bottom floor of the tunnel, the other the top. When they meet up, both will have their own mobs attacking them. Here is how to transfer the hate to the main tank. Have the main tank cast something on the other puller, haste, etc. Have the tank cast phalanx and /heal. After a resting tick or two the mobs will turn and all of them will attack the main tank. The secondary puller can now either go pull more mobs, or go job change if they're going to participate in the smn burn.
Now for the actual burn. The smns (at least 3) sync to lvl 12ish, summon shiva and 2hr. You must summon and 2hr FAR away from the mobs in case you could pull hate. After astral flow, run up diamond dust, then run back, pop a hi-ether or a mp drink and rest. While the burn is going on, have the rdm spam a few more bar- spells. If needed the rdm can throw out active cures such as /ma "Cure II" (instert smn name here). About 90% of the time, I have found that spamming bar spells during the actual killing is more than enough to keep the mobs interested in the rdm and not going after the smns. Rinse and repeat a few more diamond dusts and watch the 30k plus exp roll in. Enjoy. :)