[VHFcontesting] Dumb question about Mirage amp

[k4gun at comcast.net]

I am aware that this is a dumb question.  I'm asking it here because this crowd seems to be a lot easier on new guys than some of the boards and you guys are a lot more likely to actually know the answer.  My question is about hooking up a Mirage amp to my IC7000.  I found a model B-310G for $100 shipped and figured for that price, I couldn't miss.  

So here is my problem.  There are three connections on this unit.  The SO239 connectors are clearly marked for the radio and antenna.  The third input is marked "Remote Keyer" and it appears to be a 3.5mm jack.  Not wanting to mess anything up, I went to the Mirage web site to see what I was supposed to do with this.  I downloaded the manual and discovered its a remote keyer port.  I'm serious.  That's all the manual says.  There are no instructions on when this should be used.

So the question is, do I need this?  If I do, which port do I insert it into in the back of the IC7000?  I have a keyer port and a "remote" port back there, both with 3.5mm jacks.  Finally, will just a standard audio cable with two 3.5mm plugs work or do I need something else?

I feel retarded for having to ask this.  Its my first amp and I really don't want to mess anything up.  I wish the manual gave a better description of how to hook up and use the unit.

Steve