Its simply impractical....I worked with that system for a few years. Bob is quite correct....as you know the FOV typically holds no more than 1 or two stars so you
really need to know what your doing and have superb aiming. I was fortunate and used a Planewave Ascension mount, which I still have, and always got my star.

The best you can do is use TSX to aim the scope, then use TSX to center the star. As you are surely aware, you can move that pick off fiber in the FOV where ever you like.
I always put it in the dead center. Then TSX can dump the star with ONE click right on it. Worked like a charm and saved oodles of time.

I had it down to a science and on a good night could pop off ten objects! Of course I was using a 24 inch scope, still have that too, small ones make it tougher.
Tried with a 20 inch could barely do mag 7 and at that took to darn long. Cosmic hits would wreck the orders.

Used a 30 inch scope WOW was that a delight, but that one was at the local college.

Well enjoy, getting the data is cake, its reducing it that's a bugger. Oh, one other thing, I kept my eschell inside a freezer I bought at Sears, kept it at 20 deg F.
Then in the winter the freezer hardly worked at all, and in the summer it worked a bit harder BUT the temp was always PERFECT, and as a result those orders
and lines didn't move a BIT was much much easier to reduce the data because of the superb temperature stability.

If you go the route of the freezer, be aware NOT to open it up after the eschell had cooled or you'll get condesate on the mirror. To avoid
this, just open it enough to get your arm in the focus. I did this and had no trouble after I learned the hard way NOT to open it and pull it out!

HTH
Peter