Instead of taking classes you find the material you want to study online. You don't attend a uni, you study in your own time. You don't pay for classes, you source your own learning material. Then you pay to sit an exam at the same time as a universities' students are sitting it. The unversity grade your exam and you gain credits. Then, when you have enough credits you apply for an open degree and ask to transfer the credit over.
What i like about this idea is it seems less expensive than full time study and since you are dictating your own learning schedule then there is a chance of gaining a degree faster. I think it does sound like a lot of work though.