I'm not sure if this is what you mean/need. You can select a group of verts and invoke the scale tool.. this will usually set the scale tool/pivot point to be in the centre of the selected verts. If you then push the insert key(to take you into pivot point mode) you can then move this point around using the red,green,blue arms of the pivot tool... then press the insert key again to take you back to the scale tool... you will now be able to scale around your new position...(the only problem is that Maya will not remember this set up, as soon as you come out of the scale mode)