Registry key to set a Roaming Threshold/Trigger under Windows Mobile

Can anyone tell me if their is a registry key available for the AR6000 family that can set a "Roaming Threshold or Trigger" on a Windows Mobile device? The Programmers Guide says you can set a trigger through the hardware but that's no use to me. I would much rather use a registry setting as many of the wireless vendors do. Presently the Windows Mobile device won't roam until its in a -90dbm range even if another AP with a -60dbm is within range. 10-20 seconds of continual missed pings is observed.