How hard is it to fix a front sway bar on an '86 Accord DX that has just been disconnected on the passenger side?

If by "disconnected" you mean unbolted, and if by "fix" you mean re-bolting, then it's not hard. It should consist of an endlink, which is typically just a bolt that connects the end of the sway bar to the lower control arm. Endlink bushings should sit on either side of the sway bar and on either side of the lower control arm. If you look at the way the sway bar is connected on the driver's side, it should be easy to figure out.