I think that in this case you should create a plugin to do it, that should be better than using Global template. Let take a look at the attached file which is the LetterSearch plugin.
First of all you have to install this plugin, and then create a link like: <a db.cgi?do=search_results&db=<%db%>&let=a_letter&col=column_name">A</a>. That should list all records staring with A letter.
Hope that helps,