I think there there are a lot of easier ways to do this--the easiest perhaps is just to collect melodies and classify each one based on the structure of the lyric that goes with it, as Burke has explained, this is done in the Sacred Harp Hymnal. Then, when you come across a lyric, you just count the lines and figure out the meter.

The thing is that whether you develop a computer program or not, you are still going to have to collect songs and analyze them manually, before you can create a data base.

I suppose you could create a program that figures out what the meter and number of lines in a verse is, but you'd have to enter everything syllable by syllable, and notate it in a way that would indicate whether the syllable was accented or un-accented, so you'd still do most of the work off line--