I've just installed mine into a new tour-x also and it was very easy.
My tour-x is a medium, whereas my other arai (RX-7XX Corsair) is a large. Interestingly, the autocom speakers fit easier in the tour-x and dont press against my ears as much as they did in the corsair - not sure why this is, but the tour-x is definitely a much better fit for the autocom speakers.
Install is a doddle, just pop out the cheek pads - they have recesses for speakers already - just pop the speakers under the cloth covering - no need to alter anything. The position of the speakers always seems to me to be much lower than expected (roughly in line with the slot in the cheekpad for the chin straps, but this is the right position.
I have however found that the vox cuts in too easily even with the sensitivity wound down as far as it will go. Autocom have suggested I reposition the background noise sensor which I will try shortly. Failing that I will likely revert to ptt.