We typically use a couple of routes... one is about 450mtrs long and we just go up the road and down the path, constantly for the duration. In a 25 minute session would probably manage 8-9 "laps" depending on speed.
Also have a 1.5km circuit which is about 600mtrs up, 600mts down, 300mtrs flat to link back to start.
I'm not sure the specifics of the course matter so much, its just that it is a constant effort rather than uphill or downhill specific reps....