See Scottish Glossary. Useful, but no substitute for reading the stuff, with, if you really need it, the aid of a decent dictionary. (Alexander Warrack's Scots Dialect Dictionary is as comprehensive as most people will ever need). Do think twice, though, before singing songs in a form of language that doesn't come naturally to you. Understanding a song is far more important than learning to ape the pronounciation used on a particular recording of it.