Can I forcibly change where iTunes keeps my mobile applications?
You have to go into advanced preferences in iTunes and you should see a box displaying your current iTunes Media folder location, with a button prompting you to change it.

If you select your folder there it should work for you. 

EDIT: 
A better way to move your iTunes content, is to move your entire iTunes library (you ~/Music/iTunes folder) into a new location. Then close and reopen iTunes while holding the Option key, when prompted to choose an iTunes library select the new location and everything should be stored in that new iTunes library folder (you can actually name the folder whatever you would like).