Method is simply to replace MENU with APP_SWITCH in Generic.kl
Tested with TWRP and Google Edition 4.4.2/Hyperdrive RLS15 4.3.
You will lose access to settings menus, so use your preferred alternative method to access them. I use Gravitybox to set long press on recents key to menu. You need to change settings for recents key, not menu key in Gravitybox/whatever you use.
Mostly just for convenience since I always do this when flashing roms anyways and I think it's ridiculous to have to hold the middle button for 2 seconds to switch apps. I just add menu_switch to queue after whatever rom zip I'm flashing.
menu_switch.zip - changes menu key to app switch/recents key
menu_revert.zip - reverts changes