There is one new entity, the "tf_logic_arena" its apoint entity, not in the FGD yet so if you try to make it you'll get the obsolete thing, but thats fine, give it one keyvalue "CapEnableDelay" then its value is the seconds it takes before the capture point becomes unlocked and ready for capture.
The spawn doors are opend by this entity, as are the big blast doors when the cap becomes unlocked, output goes like this (respectively)
OnArenaRoundStart | spawn_door_1 | open
OnCapEnabled | blast_door_1 | open
OnCapEnabled | Capture_hologram | showmodel
The last one turns on the capture point hologram when the capture point is enabled, this is a minor thing but kinda works.
Other than that everything is much the same as a normal CP map, you've got respective counter entities for each team and a game_end.