My current thought (though I'm open on this) would be to support all the functionality via passing an array of objects to ORDER BY:

.orderBy({column: 'age', order: 'DESC'}, {column: 'name', collate: 'Latin1_General_CI_AS'})

And to add .asc(), .desc() and .collate() convenience functions which augment the column most recently passed to .orderBy():

.orderBy('age').desc().orderBy('name').collate('Latin1_General_CI_AS')

See #39 for more details.