I recently purchased a 6000 watt portable generator and need to install a transfer switch. The problem is my meter can and Service Entrance panel are back to back and the Service Entrance panel is flush mounted in drywall in my attached garage. All of the installation videos that I have watched show the SE panel being surface mounted or in an open wall.Is it possible to mount the 3 prong generator cord connector box to the meter can and run the wires through the meter can to the SE panel and then how would I interface the surface mount transfer switch to the flush mount SE panel?
No, you shouldn't feed load side equipment through the meter enclosure.
As an option, most panel manufacturers make a generator lock out slide that attaches to the panel and doesn't allow the main and generator breaker to be on at the same time. It is a simple piece of stamped steel but you panel dead-front must be modified to attach it.
In this setup, the generator breaker must be the top right or left (depending on the panel manufacturer) breaker.
Return the transfer switch and save some money.
Good luck and be careful!
You're going to have to open up the drywall, to connect the whip from the transfer switch to the panel. Just open it up enough, so that you can also install your inlet and wiring.
Drywall is cheap, and easy to repair. Just make sure you install it properly, to maintain any fire rating that's required.
Who recommended a surface mount interlock? That makes things harder and it seems like a misfit for your application.
First option, I would evaluate a combo meter pan/generator interlock. http://www.ronkelectrical.com/meter-rite-double-throw-switches-with-meter-socket-7103ms.php
Second option, I would contact the manufacturer about getting a front plate that includes a generator interlock. Here are many pictures of such things.
The interlock will require that you put the generator "main breaker" in a specific location. So you would need to move some stuff around and possibly use duplex/double-stuff breakers on a few circuits.
Now your generator wiring will enter the panel just like any other branch circuit, and be wired just like adding a branch circuit. (Except with an inlet instead of outlet, of course).
Doing it through the existing meter pan is complicated because you will probably need to consult with your power company as to what they will permit. As such, I doubt any of us can answer that.
Could you feed the generator via an unused knockout on your meter pan? Sure, it is mechanically possible. Could the generator wires be added to the pass-through hole? Maybe. Will your power company or AHJ allow this? Shrug.
I will tell you what I did for my generator hook-up. I chose 8 critical circuits; refrigerators, freezers, furnace, some lighting/ receptacles, to be powered in an emergency. I removed these circuits from the breaker panel. I tied together 8 receptacle boxes and installed 8 - 3 way switches into them. I fed the generator feed into 1 side of the 3 way switches, the other side went to the circuit breaker panel and the common went to the load. I added a small breaker panel powered by the generator, with a load wire running to an outside plug. When the power goes off I move the generator outside, fire it up , plug it in, switch the 3-way switches to the generator position and SHAZAM, I have emergency power to my critical circuits, and the circuits are isolated from the main power source by the 3-way switches. Is it code, who knows? But it works.