Sequel allows you to eagerly load custom associations, giving you complete control over the eager loading process.
Eager loading custom associations is done with the eager_loader option, which takes a proc that accepts 3 arguments, a key hash, an array of current objects, and the dependent associations to eagerly load.
Obviously this is a lot of code to absorb all at once, but I'm going to break it down piece by piece, and hopefully show that it is fairly straightforward.