Mike, I am assuming you are speaking of the v2 Spotlight so all of this goes in reference to the v2 light.
The spotlights were designed with using pigtails only. We have adapters in production that will be available in the next 2 weeks for everyone to convert their cat-5 to pigtail connections (or visa-versa). All the Rainbow lights share a common poisitive connection (+12VDC). What that means is the black wire on the pigtail is the +12VDC connection. That black wire should be soldered to the "COM" hole of the light. The other colors (red, green and blue) control each color's negative side and get soldered to each hole as labeled. (I always believe that all DC devices should do their switching on the negative side, so all the lights are designed that way).
Now, if you are wiring the lights to a controller other than the Brain, (ie: Lynx MR16, LOR DC controller, d-Light DC controller) they all share a common positive connection. This means that you only need to put that black wire on one of the 3 channels positives jacks. For instance a typical non-Rainbow Brain setup would look like the following:
Channel 1 + Black wire
Channel 1 - Red wire
Channel 2 + empty
Channel 2 - Green wire
Channel 3 + empty
Channel 3 - Blue wire
If you are using the Rainbow Brain and want to make connections with cat-5 cabling, than you will do the following:
Channel 1 + Orange Strip
Channel 1 - Orange
Channel 2 + empty
Channel 2 - Blue
Channel 3 + empty
Channel 3 - Brown
Again, you only need one wire to handle the positive side.
Hope this helps a little bit more.
Greg
