This is my first thread and i know there have been many, many others who have started
one on this very same topic - but am so excited about this mod
i dont recommend this to starters as the power is unecessary if you are still
hovering - but for agressive/3D its a must!
bought secondhand Eflite 20amp ESC and Eflite Park370 Inrunner Brushless motor w/8Tooth pinion = 30bucks! [hooray 4 ebay]
i dont have a pro version and this is how i did it

1) soldered a spare servo lead on to channel 3 [just black and yellow wires - dont need red bcos ESC is powered from battery]
2) put motor in [which is so light and small you think its guna be pants!!!]
3) connected ESC lead to 4in1 [used paper clips to join as both connectors are female and wrapped tape round]
4) made a Y harness from battery to 4in1 and ESC
5) away you go

the power is fantastic and if you get into trouble you can just blast off away from tree/ground etc
have dual tail and have to say it performed admirably
because mine is secondhand the ESC had been setup so if anyone else has good settings for this speed control please post!
i will be 'trying' tictocs/low 'e' loops[am ordering spares now!] - so look out for vids near future

WARNING - the brushless 'arms' real quick but the tail esc/gyro in the 4in1 takes longer so if you do this and
forget to wait for the tail your guna be doing some advanced piros quicker than you intended!

this has been so useful and am always forgetting so im guna put this here
THE CHANNELS - [taken from previous post]
1 left rear servo
2 front servo
3 main motor ESC
4 tail motor ESC
5 is unused [but is gyro adjust on PRO]
6 right rear servo

im goin flyin' - thanks for reading MG

yeehaw! glad to hear you are having fun with that setup. i'm very close to investing in a brushless main and tail for my cp2 too. i'm just trying to see if i can wait to get a tx first so i can go with a hotter motor. the lack of headspeed exiting had maneuvers with the stock setup is starting to drive me crazy, not sure how much longer i can wait.

im using stock tx/4in1 and it works fine - know what ya mean bout headspeed

Here's a schematic which involves seperating the receiver from the 3-in-1, and using extensions to connect to the brushless ESC and the rudder to the 3-in-1.
Cutting the red wire in the extension is the easiest way to seperate the brushless ESC from the tail motor ESC in the 3-in-1.
For a different receiver, remove the Eflite receiver and plug the new one in using this same scheme..
Note you will have to check the main rotor rotation after assembly. Swapping any two wires from the ESC to the motor will change its direction of rotation.

nice diagram

I haven't upgraded my CP Pro to brushless (yet!) but I got a taste of the difference today between brushed and brushless motors. I'm getting my Walkera 36 back in action and put an Align 430L and ESC in it along with a Spektrum DX6. Got an extra Rx for the CP Pro - it gets "Spektrumized" next week. Anyway, I had a brushed motor and NiMh in the 36. It could barely lift off the ground. With the new brushless setup, the power is unreal! I haven't flown it yet (way too much stuff to adjust still) but I held it down by hand while running up the throttle. The headspeed is scary fast and when I hit full throttle/collective it really pulls HARD. Can't wait to fly it! Since I'm still learning, I'm going to have to tame it down big time with the radio until I get better. The CP Pro is next! I can now imagine now what a CP runs like with brushless.