You don't actually need to tank Bloodsail rep to get Steamweedle rep.
You can get Exalted with all four factions simply by farming Ratchet & Gadgetzan rep and have it spill over.
Because you can't farm Everlook directly, you will need to get that 42000 spillover rep anyway.
I personally preferred the harbors in south east Tanaris for the farming.
At level 90, this should cost you about 20-30 hours, depending on class, and another 15ish hours doing the BB bruisers.
As long as you do all the daily and weekly quests it goes pretty fast (rep/hour wise) and won't cost you any gold.
Just be glad you didn't need to buy epic card decks to get 350 rep per turn-in!
This should be the easiest reputation to hit of all.
You should really grind to honored first before you farm lockboxes.
If you know an engineer with a mailbox, have him come drop one next to you to save you running back and forth 50 times.
The best route I found for picking boxes in BRS is as followed:
Go up to the rune room on the left, then back under the bridge and keep going through the entire dungeon.
As you are running back there are several ledges that you can jump off and shortcut back to the entrance. Pick one and start picking pockets again from there (The pockets should have refilled as far as the first boss atleast, depending on your speed)
Besides using /targetnexttarget macros for pick pocket & sap, my biggest speed increase was the addon called TrashCan, which auto-deleted useless stuff to keep my bags free.
I'm not certain if the quest reward you get is still unique, but if it is, make sure you macro that as well to burn through those boxes even faster.
The rep farm took me about 15-20 hours, with another ~90 hours extra for the lockboxes as they had tanked the drop rate just as I was about to start on them (Was lucky to get 30 in an hour back then). Considering the extra focus pick pocketing requires over straight up farming, I stronlgy suggest people start with this if they are going for it. Once honored you can alternate lockbox farming with the straight up rep mob farming on your main.
PS: If you make a personal guild on that alt of yours, you'll have an extra guild bank to store those boxes in.
Big ups for the truly insane people that farmed this when it was still available. A full Dire Maul clear netted you on average about 200 rep ... and it was the only increase you could get other than the original Quel'Serrar chain. This was by far the hardest grind to do back when I did it, which took me over 200 hours to complete.
Hope the extra info helps you and anyone that wants to start on getting this glorious Feat of Strength