this will work  on the lod_lo but does nothing to lod_hi. I dont get any errors so Im not sure what it doesnt like. 

def LodSet (db,par,rec,userdata):
     try:
          if mgIsCode (rec,fltLod):
               name = mgGetName(rec)
               if name == "lod_lo":
                    changes = mgSetAttList (rec, fltLodSwitchIn,50000,fltLodSwitchOut,15000)
                    if name == "lod_hi":
                         changes = mgSetAttList (rec, fltLodSwitchIn,15000,fltLodSwitchOut,2500)
          return MG_TRUE


db = mgGetCurrentDb()
mgWalk (db, LODSet,None,None,MWALK_MASTER)