Are focus frames even possible in Classic Wow?

[MinguasBeef]

I know for vanilla wow, there were focus frame addons to be able to see a second unit's hp/mana/castbar/etc.

However, is this even possible for the classic beta?

It seems that functions like UnitHealth will only work on a party member or your current target.

When used on someone not inside of your group, the function returns 0.

Any ideas?