I've only successfully done this in Pool of Radiance (I was doing OK in Curse but the dungeons kept getting screwed up for some reason). It's actually a pretty good challenge if you're short on time because many random encounters will shrink down considerably as well and the game goes faster.

Obviously I used a half-elven cleric/fighter/mage (you can do it with an elven fighter/mage/thief but it is harder). You can level yourself up to level 2 pretty quickly by making a beeline for the treasure room in the NW corner. After that you should take on the minor encounters in the slums and rest to clear out the slums and Kuto's well random encounters, and go from there. Sokal keep should be put off until level 5 mage so you can fireball the big encounter.

A key thing here is to visit areas of treasure in the correct order as your carrying capacity will be very low. For example, while Kovel Mansion is a good place to raise XP, you should avoid opening the cabinet with the scrolls in it until you are level 5 and can scribe any spell you find. Similarly, you should go to the outpost of Zhentil Keep at the end to pick up the joined potions of extra healing on the commandant's body, as you will need them to help heal yourself after defeating Tyranthraxus's 8th level fighters.

Has anyone else tried this?

I'm actually trying this right now in Pools of Darkness (Human Paladin 39/Magic-User 40 dual class, Magic-User currently at level 20 as I'm starting Kalistes' Dimension). The Ring of Blinking makes it really easy most of the time. I have to imagine that the Blink spell is potent for solo characters in the earlier games, too.

I've seen some youtube videos of solo runs, so it isn't too out of the ordinary. Still a nifty challenge either way!