So you can do this in one of two ways:
1). Burn Trollgore down before Consume reaches 10 stacks.
If your group is packing a ton of DPS and/or a Bloodlust/Heroism, Trollgore is probably going to die before Consume gets beyond 5 stacks. If your DPS are capable of reaching 2.7-3K DPS or more over 30 seconds, this is the easiest way to get the achievement. Pop trinkets, use your cooldowns or a Bloodlust/Heroism if you've got it, and the achievement is fast and easy.
2). Kill adds and then line-of-sight him so that he can only Consume a few things at a time.
The Wowhead commentary thread provides a few good suggestions on how to do this (Magekill's comment is especially helpful), but my favorite is keeping Trollgore tanked to the left of the stairway behind a column. Make sure the adds die, and then have everyone but the tank (and, if needed, the healer) LOS Trollgore until the first Consume. DPS Trollgore for 12 seconds, then LOS him again for the second Consume. Lather, rinse, and repeat until he dies. You should have more than enough time to get him down before Consume (slowly) stacks to 10, although obviously this will happen faster with DoT-based DPS.
This is one of the easiest achievements in the book. Novos doesn't attack your group directly until all four of his shields are down, and they blow out -- one each -- for the humanoid adds that Novos summons from the side entrances of the room. Because these adds will aggro onto your group no matter where you are, it's a fairly simple matter just to keep your group on the stairs and DPS all the adds down there. An OT might be helpful for the elite constructs that occasionally spawn, but it's really not necessary because the summoned adds' damage is mostly magic and fairly low.
Better Off Dred
I would advise not attempting this achievement unless your group has a decently-geared tank and healer (or an off-tank). A Warrior tank and a Priest healer is the easiest possible combination to deal with Dred's fears. Regardless of who you've got, if you're planning on having your MT tank both Dred and the adds, be prepared for this player to take -- and your healer to have to compensate for -- a respectable amount of damage.
There are 7 raptors in Dred's pen. While Dred will use an ability (Call Raptor) to force an existing add to aggro onto your group, he doesn't otherwise summon any; what you see when you step into the pen is what you get. You have to kill 6 raptors for this achievement, so before aggroing Dred, set your group up and discuss who's going to pull additional raptors and where to regroup if you don't have a way to deal with the fears.
If your tank is pulling the raptors: Have the tank aggro Dred when he paths back, then the raptor closest to the entrance. Kill the raptor. If your tank is responsible for pulling additional raptors, he/she can start to maneuver Dred around the pen to pick up additional raptors which the group will kill one by one until you've gotten 6.
Having done this, however, I have to note that Dred is so large that it's difficult for a tank to see exactly where they're going and how many adds likely to aggro at a time (even if you've enabled pop-up health bars on enemies). I'm also not fond of it because dragging Dred around his pen risks Fear sending players into raptors you weren't planning on pulling yet. So while this is doable, I still recommend having --
DPS pull the raptors: If your DPS is going to pull, you can tank Dred outside his pen and wait for adds to be pulled to the tank, then taunt. This is less risky with Hunters and Rogues who can Misdirect and Tricks, but should be manageable by any class that can pull at range. However, if your tank or healer is in mediocre gear and you have an OT-capable class in the group, you may want to --
Off-tank the raptors: The reason that tank damage can be a worry here is that Dred applies a debuff that increases bleed damage taken by 75%. This can be applied on top of his other debuff that reduces tank armor by 75%. If you add a Scytheclaw (which applies an ugly bleed) or Gutripper (which can reduce stamina by 15%) to the mix when one or both of these debuffs are up on your tank, healing can get hairy, particularly if the group gets Feared in the meantime. Off-tanking the raptors keeps both sets of debuffs nicely apart, but make sure your main tank also hits the adds at some point to get on their threat table.
As others have noted, for some reason this achievement seems to be a little buggy even if all 6 raptors are killed with Dred still alive and safely aggro'd on your group (I've had it happen to me twice), so if you don't get the achievement, keep trying.