I had an idea while messing around with the construction set. What about awarding a very small amount of exp for unsuccessful persuasion? I've tested this with a character that had speechcraft as a misc skill with values of 0.03 and 0.05 and it took 4 minutes 40 seconds and 5 minutes and 10 seconds respectivly to level it up from 5 to 15 with the aid of autofire on the left mouse button.
It makes some sense as it seems plausible the character would learn something even from an unsuccessful attempt at persuading someone and it takes a little bit of annoyance out of speechcraft by making those several hundred failed attempts to admire someone you'd already driven to 0 disposition with the first few attempts to admire them actually give you something other than carpal tunnel syndrome
Obviously, the difficulty is in finding the correct value: too low and it will be utterly pointless, too high and it will be easy to level it up.
BTW if anyone else wants to test this with autofire like I did, I used AutoHotkey with the following script in the codebox below(note that I didn't write this script, it was written by another Morrowind player). The program comes with a sample script, just right click on the icon for that script and click "edit script" and replace the text with the stuff in this codebox. If you need any further help, the programs' website has a forum.
;; AutoHotkey Version: 1.x; Language: English; Platform: Win9x/NT; Author: A.N.Other ;; Script Function:; Template script (you can customize this template by editing "ShellNew\Template.ahk" in your Windows folder);#NoEnv ; Recommended for performance and compatibility with future AutoHotkey releases.SendMode Input ; Recommended for new scripts due to its superior speed and reliability.SetWorkingDir %A_ScriptDir% ; Ensures a consistent starting directory.LButton::Loop{Click DownSleep 50Click UpSleep 50If(GetKeyState("LButton", "P") == 0)Break}