Just wanted to add my bit, I will add a more detailed spec etc
I struggled to get to 50 toughness but with a bit of platinum I managed to get to just over 50 Toughness and start tanking. I have tanked FC and managed it all although the last boss was very tough so another member too this over and even they struggled. After this run I have shot up to just under 80 toughness.
I would say that you need to just get in there when rough tanking you need to make sure that you have an AOE macro set up and get ready to blast that out a few times if there are group of 2 or more mobs, if you just keep doing this then you should hold the agro and your finishers will effect the main guy you have selected.
Another tip will be to get your Guard up asap even if this it with just two points and then put it up with 5 but keep an eye out on when this is running out as you will build up your points very quickly and it might be better for the healer if you can aid with a protection attack which will absorb a certain percentage of the damage and give it back as healing so this is great aid to the healer or just attack it.
I my experience so far and from tanking in WOW even from a druids point of view you have to be pretty switched on a rogue to be able to tank as I have found that you can lose agro quickly from multiple targets if your not aoe'ing enough. A single target or a boss I have found pretty easy due to the amount of dps that we can output gives us the edge on other tanks on keeping the agro and aiding with DPS.
More to follow but this is me so far. Let me know what you think and if you have any questions.