In this case, you're "outside" of the RAT teleport system for an individual player. So you'd create a new event (leave that one alone, its for each persons individual teleports).
Conditional:
STARTSWITH:!coliseo
Script:
teleportplayer {player_steamid} {tele_coliseo}
Please check for errors, I'm at work so I could have a variable name off, etc.
Then when a player were to type !coliseo they should be teleported to the destination you've setup in the admin teleports.