One table, many references

I'm a total newby to Ruby and jumped into an application that quickly went over my head. My question relates to how I can setup the models in my app so that I can reference the same database table using different names. Here's how my database is setup:

table requests   id   title   sponsor_id   initiator_id   implementor_id

table employees   id   fname   lname

The sponsor_id, initiator_id, and implementor_id fields are all intended to reference an row in the employees table. I'm confused as to how I make rails understand that these foreign keys all reference the same table. Can anyone help?