module for description of sequence variants (where to place code)

Hi

I'm writing a perl module to write a description of the variance
between 2 sequences as described on
http://www.hgvs.org/mutnomen/recs-prot.html

Basically, given 2 sequences, would returns something like "p.Lys2del
p.His25_Met26insGln" if those are the differences. It also accounts
for the existence of - characters on the sequences that may come from
their alignment.

My question is, where on the project tree should I place the module?

Also, is there something already written that would convert from 1 to
3 letter code?

Carnë