Quick home studio and lighting??

In the next few weeks I'm going to be taking a couple of portraits of my friends very similar to these -
http://www.mymodernmet.com/profiles/blogs/before-and-after-shots-of-jogg 

I'm looking for some advice on what lighting I should use and how I should set up my work space. Obviously we can find a large white wall to take the photo against, the only kit I have available is a tripod and a canon 430ex ii flash gun, so I son't really have the option of using a slave flash mounted off camera (as far as i'm aware)

Does anyone have any suggestions?