No, there is a version of it as an add-on and functions with in-game !ascii commands. Trust me, i use a mac.
I actually take issue with the first half of your post. There's no way
!ascii or
@bt or whatever text to spam brick converter you have in your Add-Ons folder could be interpreted as brown townogue to a program called "image to brick" at all.
I don't actually understand why people are stuffting on you for saying "Trust me, I use a mac." Exe files don't work on macs, so it's obvious that if you were converting images to bricks (which, you aren't, by the way) you'd be using a method other than img2brick.exe.