where would you put the two button extension?
holding on my hand...
Seriously, I assume you mean how do I wire the two buttons?
The thumb cluster of the ergodox have two spare sets of holes for two additional keys, I just solder the diodes and the cable to these holes. It is really very straightforward.
Using tmk firmware, the two buttons can function as 4 keys now (with the ACTION_LAYER_TAP_KEY(layer, key) function), which is kind of neat
However, I think pedals can serve my purpose better, and freeing my hands from web browsing. actually the pedals I ordered just arrived today. will try to connect them to the ergodox after the holidays.