Well, I've been using this for a year now, and its pretty stable. I thought I'd like to release it. You can simply drag a NARC file onto it to load it, or you can click open NARC. The delete file does not work (not that deleting makes any sense...) Added files go onto the end of the NARC. This supports replacement of any file of any size. And yeah, that's all...
Download:
http://projectpokemon.org/editing/misc/alphanarc.zip