So mine is getting pretty bad and i figured i might as well see what the best method for doing this would be....
they're available at most auto stores. $10-$15 around here. really simple. spray on the cleaner, let it soak, rinse it from the inside, let it dry, then spray with new oil.
Like everybody else said, just follow the instructions on the K&N filter re-charge kit. Very simple and easy to follow instructions.
Only spray the oil on the outsid of the filter... If you spray the inside your MAF sensor will hate you