Hello... Well I'm a ol maintenance man that had a solding iron in my hands at 12... The way I would do it "pretty" would be to
1) mark your Molex connectors with wire color and Location. ( sharpie/masking tape )
2) remove the pins first from the molex connectors, it is done with a "Pin Pusher" ( which I have a set of ). *
3) cut the pins off and strip a little insulation off One set of wires... JUST One SET!!! we need one set of pins for each color of wire.
4) Match the colors, Solder a stripped wire to the BACK of the other matching wire pin. **
5) Re-insert the pins back into One Molex connector.
*There are two Tangs on each pin... it takes a round tube the size of the pin to compress the tangs to remove the pins. Sometimes a ball point pin end has worked for me... But you don't want to break them off... or go into high anxiety... but there are in-expensive tools to do this.
http://www.youtube.com/watch?v=TcV7l1pER2M
**Another tip is to open up the the insulation crimps on the pins before soldering the new wire to it... this will keep the insulation from melting when soldering, and also gives extra metal to solder too... after you are done you can squeese the insulation crimp back around both wires.