Theoretically you could write a program which does GoTo using the ST4 on your laptop.
The biggest problem, even if you could do this, is that the ST4 commands work around the tracking speed (15"/s). This is very slow for GoTos.
An alternative approach is to build your own controller with newer motors. It is not very expensive, but needs some working knowledge of electronics and computers.
Take a look at ONSTEP
I have done the iterative platesolve/manual movement by hand, and it gets easier if you use the RA/Dec setting circles to measure approximately the amount you need to move.
In the end I built a platesolving GoTo which automates the same concept.
Thanks for sharing. I admire these DIY GOTO efforts and believe the outcome is exactly what lots of amateur astronomers expect. Although it's far beyond my reach in knowledge, I have saved the pages for further digestion. Thank you so much!
Given my limited knowledge and gears, I am thinking it more practical to accept the advice of using the setting circles in combination with plate solving. I probably won't need too many iterations until I somehow locate the target in the view.
I'm using my rudimentary thinking to try to devise a makeshift technique. Is this going to work out?
1. Orient my imaging camera in line with the scope, so any stars' horizontal motion is along DEC, and vertical is RA.
2. Place a bright star, say Vega on the top/bottom edge of the FOV so I can see it in live view.
3. Press RA+ or RA- on the small hand controller the moment I begin timing.
4. Average the time it takes for the star to travel from one edge of the field to the other, and divide it by the height of my FOV to get the "seconds per arcmin" or even finer units.
5. Do the same on DEC direction, taking backlash into consideration.
So I can coarsely math the time I need to press on the RA and DEC button if I want to move my scope to the desired target. This sounds like using abacus and typewriter in the information world, but I'll give it a try as I think it's going to get me somewhere near my target.