*blush* I felt little like you after I found out after FOUR months that I have not been cleaning BEHIND the ear, in that little crease, right!!!!! Sure, I did the whole wipe behide the ears, but I never LOOKED. So while letting her bottom get some sun one day, I notice the gunk!!!! Major neglect!!
I just wet the tip of a baby cottonbud with some babyoil and apply before bath time and afterwards just wipe with a cloth. Mind you, she is now 10 months and it's getting easier. I just rub her ears with a wash cloth in the bath and volá - squeaky clean.
I tend to agree with Kim and Snacks - the inside of the ear canal will clean itself, just pick off the wax that are on the outside of the canal, kwim.