Workers should not be elevated on the forks of a forklift. A forklift
doesn't have a holding (lock) valve in the lift system and is not designed
for a person to be on or under forks if elevated. If some one gets hurt
you will be open to some major legal problems if in the U.S.. You can rent
"manlifts" and "safety harness plus lanyard" for hoisting personal.

Or you can review the regs. It's ok to lift people with a forklift if

a) They are on a lifting platform that is secured to the lift
and
b) That platform has a proper guardrail.

With the proper rail, a harness isn't required.

http://www.osha.gov/pls/oshaweb/owad...S&p_id =21322

Running out to rent a scissor lift or some equivilent peice of
machinery every time a lightbulb needed changing would really put a
ding in a small shop's budget.