Query based on Custom Field. To create a link list?

This codex article looks like what I’m trying to do, but not quite.

I would like to add three links that will will filter the posts based on custom field, regardless of category. For example, the links would be: Sort by Max. Occupancy (custom field) | Sort by Title | Sort by Bedrooms (custom field)

Any advice? Please help!

PS-my templates all exist in the index.php file, controlled by conditionals…