Why would you drill a hole andTap con the box?

I have been gluing them in for years with your foam gun.

 I just cut it out 1/4" big and foam it set it it in maybe use a strap with a screw to hold it till it sets(done)

If you do it with the romex in and  wire channels cut out you push the wire it and foam it in also.

You value is back to what you started with ( with in reason)
 Just try to get them off after that ( in one piece) not easy to do!
Boy this nice to have all this advice and no work.
 What about the rest of you? thing are SLOW HERE in WI. any one looking for a hand?

It is a bad Idea. the electrical can be hotknifed into the ICF, and their is no need for the air space. By furring the walls you are creating a condensation point that will grow mold.

Alot of Subs that are not familiar with ICF try and make their own way, when infact all they need to do is contact a installer, or the product rep. both will be more than willing to train them on how to do things. If you have any questions please feel free to contact us at creativeicf.com