I did it - its easy. Look up on the weeb, there is a step by step doc around (well, at least there used to be a site with it). You can use any blue LED's, but you need like 6 for each deck, so its not that cheap.
Get a good soldering iron, take your time.. perhaps 3 hours to do the mod total, including deck take apart and re-setup.
Practise the soldering if you have no one to do it for you. ( Just grab and old circuit board and and practise on that ) make sure you put solder on and only on the gold or copper part of the board. make sure 2 solder connection don't touch unless there in series then its okay. If you solder and you can see through the hole resolder it so it has good connection. ( others wise it will work sumtimes and other time it won't ) make sure the solder is shiny when you apply it onto the board for best conduction. Meaning if you apply the solder onto it again to fix it then the shine will dull abit and conduction won't be as great ( but it will still work ).