Since I just got finished wiring my ACE to tow my trailer, I thought I would share the information with the rest of yall.  For starters, I recommend that you wire the bike using a powered converter such as Hoppy's 46255.  This unit does two things.  It pulles the power for the trailers lights directly from the battery and not the bikes wiring harness.  Secondly, it converts the seperate turn/brake/ running ligts of the the bike into a four wire version for the trailer.  I mounted my converter to the hinged portion of the batter box under the left side cover.  It is held in place by a couple of zip ties.  It does not interfere with the opening and closing of the battery box:



Mounting the Hoppy 46255 as shown above allows the unit to be wired and grounded directly to the battery. 

When you're ready to start wiring your bike, remove the seat and locate this group of wires just behind your airbox:



This is the junction where your tail light, brake light and left and right turn signals enter the main wiring harness.  Remove the protective boot and expose the connectors.  The are encased in protective sleeves:

 

I used the process of elimination to determine which wires were which.  I simply unplugged a set and turned on the ignition key.  I then checked the running, brake and turn signals to determine what wasn't working.  I checked twice each time to ensure that I had wiring in the right wires.  Using common male/female connectors, replace the factory connectors.  Cut off the old ones, strip a small amount of insulation from the wire, and install a new connector:

 

What you are doing here is wiring in the corresponding wire on the Hoppy 46255 with the correct wire from the bikes harness, using a two-to-one male/female connector.  I bought the gold plated two-to-one connectors from my local Radio Shack.  The wires are cleary marked on the Hoppy.  Simply attached the propper connector and attach it to the proper wires:

 

In the photo above, the yellow/green wires are the brake lights.  One comes from the foot brake and one comes from the hand brake.  The red wire is the brake wire from the Hoppy 46255.  The solid green wire they are connected to is the brake wire leading to the tail light assembly.

Repeat this process until all wires are wired with the corresponding wire on the Hoppy 46255:

   

 

When you are finished, wrap each set of connectors in electrical tape to protect them an prevent the possibility of a short between the wires:

 

Recover with the factory protective boot.  I wrapped all wire in wire wrap available at any auto parts store.  I routed the wires around the air box to make it look neat and almost factory, and secured the bundle in place in the stock location:

 

After you are finished, make sure the Hoppy 46255 is secured and wired in to the battery:

 

The wires coming from the four-wire plug on the right of the converter in the above photos is also wrapped in wire wrap and routed to the back of the bike to plug into the trailer.

After you are finished, replace the left side cover:


   
Your bike is now ready to tow your trailer!