It should be an LJ. The a/an rule isn't based as much on whether a word begins with a vowel as on whether it SOUNDS like it starts with a vowel. This is why you have A livejournal, because the initial sound is that of consonant L, and AN LJ, the initial sound being that of the vowel E (eljay, if you will).

It is, in fact, nice to be a pedant.