Off-topic: how do you clean a fuel tank?

[Josh Sirota <jss@marimba.com>]

Folks,

Some of you home mechanics might be able to help me.  My roommate and I
were recently given a motorcycle that hasn't been ridden in years.  I
have discovered that the fuel in the tank has basically turned to
sludge, clogging the tank's outlet.

A) how do I dispose of the old fuel (at least, the 3 gallons that are
still in a liquid state)?
B) how do I clean the tank and remove the sludge?

Thanks for any help.  Please reply to me directly.

Josh