The screws are the bottom black cross heads on the visor/chin piece mechanism ... once undone the cheek pads are still hooked on the locating lug ... bend the cheek pad outward as you pull forward and it will come out ... you get a much neater job by installing them with the cheek pad removed as you can feed the earpiece in from the back if you pull the liner away from the polystyrene ... it does stick back down to a certain extent ... do not use glue if it doesn't ... it won't be visible anyway...
Remember ... make the headset the weakest link in the chain ... the Autocom plugs are very difficulty to remove when pulled straight ... you don't want to either pull your bike over (seen it happen) or get pulled down the road by your head if you fall off (not seen it happen thank god)...
the microphone can be squeezed in between the cheek pad and the helmet shell at the top ... but it is a mighty squeeze ... and they don't stay put if you need to move the microphone every time you put the helmet on ... Velcro can be used to good effect but looks ugly...