I remember a D1 veteran named Langolier used to host a .dat file that would remap the spell hotkeys from F5-F8 to ASDF or something like that. Unfortunately, his website (dpsyche.com) is down and it's no longer possible to download it.
There is also a very similar mod made a long time ago by a guy named SubSpace. I was even able to download it through Web Archive using a link obtained through browsing old google groups (alt.diablo or something like this). But his mod only works in 1.07 which isn't very helpful.
Or maybe there are some windows utilities that would achieve the same goal by simply remapping the keys manually?