I've searched at about every local auto parts store and hardware store for a 6mm hex bit socket, 3/8" drive. I'm **** outta luck. Most got the 7mm bit and up, but not the 6mm. Is that just a weird coincidence?

Anyway, what's the correct sequence for tightening the manifold bolts? I'd do it in three or four steps, but where to start?

If they don't have it in 3/8" drive, get the 1/4" to 3/8" converter.

has a very weak arm.
Seriously, I've found lose nuts and bolts and vacuum hoses here and there. I don't trust anything this guy has done after finding evidence of sloppiness everywhere. He had the intake manifold out, and I'm pretty certain that he did a shoddy job with that, too. So I want to make sure that at least the manifold bolts are tightened properly.

I checked every local place (Kragen, Sears ACE, Lowe's, HomeDepot) that carries tools and none had the 7mm hex bit. I thought it was unreal, too.
I was also trying to find a 1/2" to 3/8" adapter, and nobody had that either. Unbelievable...

One word of caution, DO NOT FRICKING TIGHTEN THOSE BOLTS TOO TIGHT!!!

Why did I just scream? Because, I mixed-up Newton Meters for Ft. Lbs. on my Torque wrench and tightened the Nm specification to the Ftlb measure. While only several pounds difference, this error caused the inside of each head to lift slightly and I had oil in the coolant and oil in the valley of the engine. Major pain in the butt!!! You must retighten the head bolts if you make this mistake and then re-torque the intake manifold to exactly the proper specificaiton.

So please be careful and read twice, tighten once.

I use only the Metric system, unless I can't avoid not to.

So, where do I start, from the middle towards the end, increasing the torque in 3 or 4 steps? I don't want to warp the manifold.

I just got a 1/2" to 3/8" adapter from Kragens... it broke, but they didn't have another, so I found another one at Pep Boys. I found a 6mm 3/8" bit at Kragen's,Pep Boys, Home Depot... Kragen's had a nice set of 5mm - 10mm for $14 or so... Home Depot had a nice set for $20 with 4mm-10mm