So Aly played a character called Melody (who's wonderfully adorkable), the daughter of Lisa’s substitute music teacher, whom Skinner sets up with Bart to distract her as he tries to date her mother.
Anyone who wants to catch the episode can watch on megavideo:
Part 1
Part 2
Anyone only interested in Aly's part only needs to watch Part 2, that's when her character appears. She's only in two scenes, but it's worth a watch.
I love that she happened to guest star on such a gay-themed episode

(Neil Patrick Hairless is the funniest ridicu-dog name I've heard in a while!)