How do I set up my amplifier for remote control?

Please see point 9 of the above link.

You will need an Electronic Engineer, Good Technician or Electrician to do this.
For lawsuit reasons I have been very careful to avoid providing a whole recipe
for doing this, because i have no control over how well others may or may not
carefully follow instructions, and I will not be blamed for people doing careless things to hurt themselves.  After all, we are talking about AC Power here! Tell them that when the amp should be turned on, all 8 bits go active on that LPT port.

That being said, here is one product that may fit the bill:

You may want to go here:
http://www.electronickits.com/kit/complete/elec/ck1601.htm

and check out:
CK1601A - Parallel Port Relay Board (Assembled & Tested In The USA!) - $49.95