I am building a Savannah Mansion, and i have an elevator which looks not-so-great when the floor is default elevator texture. It would be incredibly amazing if i could make the elevators look like different blocks. Take a gander;

does the EIO painter work?

Seeing this just gave me an idea of having my entire base floor made of elevators.

Only 2 years late: dropblock.overrides - config option to add elevator functionality to any blocks. Available in 1.7.3.

Not exactly same thing (this is server-wide setting), but that's as far as I go without messing with whole 'disguiseable block' complexity.