make sure that you double check the location you uploaded your files into your phone (If you're using FAR then what you see is where you placed it...) the moment you've copied them to the proper locations and restart your phone, it should automatically be used by the phone.
MegaBass to my knowledge is only available in W series firmwares... K series does not support the function due to it not being a walkman phone. Someone please correct me on the accuracy of this information.