Not on the 'bus any more, but still have manuals which suggest to do it via lateral revision at PPOS.
I guess you Line Select 1L and that should bring up an Option to 'Hold' at 3L? I guess that you would then set the leg distance to 0, to force an orbit.
Should work, failing that do as you say and go into heading and whiz round the heading bug - saves going head down and is quicker
