I am not aware any method for that. Maybe you can try something else.
Instead of getting and remembering all the positions, as long as you know the Inport/Outport name, you can use find_system() to find that particular Inport/Outport block.
Then you can use hilite_system(BlockPath) to highlight that block so it's easy to find. There is different scheme for highlighting. I use hilite_system(BlockPath,'find') and hilite_system(BlockPath,'none') to reset it.
Some other tips for browsing a huge model. Click an empty space in the model (don't double click thought because it will make an annotation),
press key 'F' to make view fit for window
press key 'R' to zoom in
press Key 'V' to zoom out
press Key 'E' to move up
press Key 'C' to move down
press Key 'G' to move left
press Key 'B' to move right
