I would go with this for the first 40 points
http://db.vanillagaming.org/?talent#0ZxhxscMdtPut points in Feral instinct as you need to progress to the next talent level. The reason is you probably won't need the extra threat at lower levels since very few people doing DPS in a dungeon while leveling are going to have best in slot gear so their damage isn't exactly crazy yet.
You could switch the 2 points from primal fury to feline swiftness since the extra speed is pretty nice from level 20 to 30.
After this you can either put the last 20 points in resto to heal when needed or finish off a full feral build by putting it into balance for 5/5 natural weapons and omen of clarity.
Edit: This is the final full feral tank build for level 60. Some people put points into Improved thorns instead of improved enrage.
http://db.vanillagaming.org/?talent#0zLV0oZxxxscMdtV0b