First off, you should really try and 2 heal this fight. My group 3 healed to learn this fight and hit the enrage. After we swapped to 2 heal we downed him np.
Second, I wouldn't worry about tracking the buff. 2 healing will provide enough dps to kill him and the only people who really need that buff are the healers.
Now as far as who should go in:
You want to pick 2 ranged to go in with a healer each time. My raid uses our ele shammy and hunter. The idea is for them to go in with Healer 1 and just kill every single add they can for almost the entire 30sec duration. Then they pop out and go right back in with Healer 2 (or healer 1 again if healer 2 is voodoo'd).
Having those ranged stay go in makes it very easy to keep the number of adds down which will ease the dmg your 2 healers need to account for. We found melee were best kept on the boss. I dont know how mages will fare in there so this is something you will have to play with. Not having to run all over the place to kill the adds is a huge advantage though.
Now, because you are 2 Healing and sending the same 2 ranged in each time, you will rarely have to use a backup dps other than for the very first totem. As soon as you get both of your ranged inside the spirit realm they will simply stay in for 25 secs, pop out and go straight back in with either Healer 1 or Healer 2 depending on who has voodoo and who went last. Your ranged wont be getting voodoo because they are inside the spirit realm most of the time, killing adds.
The reason you need a backup for the first totem is because voodoo dolls will cast once before any totems go down. This means 1, or potentially both of your chosen ranged may get voodoo'd. If this happens just send your backup. On the next totem both of our chosen ranged will be able to go inside. After that, there will always be a totem waiting for them when they pop out of the spirit realm. Just make sure a healer is with them and send them right back in.
Simply use raid frames to see who will be getting ported when the totem dies. It is a little purple blob on default blizz frames, so I just look to make sure it is on both ranged and a healer, then I give them the ok to kill it. The only other thing to watch for on raid frames is Voodoo.
I hope this is clear. I will be glad to clarify if need be.
Lvl 90 Orc Warrior - Protection
Raid Leader - Sparkle Magic - US - Proudmoore