Guest Office - you may like to look at my program HARMONY, which transposes, and will also create Melodeon Tablature (Assuming that your Melodian is a squeeze-box). But you still have to get the tune into machine-readable format first. There are many traditional Irish and English tunes already available in abc format, which Harmony can import. A sample is provided with the software.See my site at www.greenhedges.com to download a copy.
New features in the next version include a 'reel to hornpipe' converter, because so many hornpipes have been incorrectly transcribed as reels!