Join overhead 2000' agl, then (assuming left hand circuit), turn left overhead to position yourself over the centreline (in the t/o direction) and descend over the centreline. Fly a standard circuit pattern, descending, aiming to be at 1500'agl overhead the normal turn onto xwind, and 1000'agl over the usual turn onto base.
Very similar to standard overhead join, except you descend over the centreline, not the deadside.
Where are you flying to/from?