How to model deals you weren't a part of?

I see a lot of people mention when they're applying for analyst positions that they'll model out a companies deals and send them along with their resume.

I think this is a great idea but had the following questions:

• Where do you find the information to model the deals with? Loopnet, their website, contacting them, or somewhere else?
• How in-depth do you get with your model?

Thanks!