Decoder fitting for Class 57/0 Diesel 57003 Freightliner Evolution

[bazsad]

I recently purchased this engine (Backman catalogue number 371-651). I wish to convert it to DCC by installing a decoder. I have done this a number of times on OO gauge but this is my first attempt in N gauge. THe engine has a circuit board on top but no apparent connections for DCC hook up.
Where can I find instructions on how best to accomplish this task? I am anxious not to damage the engine by going about the task the wrong way. Is there anyone out there who can help?