So how do you go about checking both PT and FT but letting them know that you really will take either?
Send an email to admissions, letting them know you would like the committee to consider you for both full and part-time. After you finish the email, call to make sure they received it and reiterate your intentions.
I own a small internet based business. If I go to law school part-time and continue running my business during 1L, with scholarships, I can keep my debt in the $0 to very minimal range. The problem is that my business does require a time commitment. I wrote the email and included a paragraph addendum attachment with the email explaining my situation. I then requested all scholarships be considered for part-time, on a prorated basis. I was very polite and so far, every school I was accepted to and seriously considering was receptive (couple of T1s with part-time programs and T2s) and almost immediately replied telling me that my request was fine.
If I explain during a BigLaw interview why I decided to go part-time my first year, I can't imagine any potential employer taking issue with my situation. If they do take issue with it, I won't really care because I will have $0 debt and be able to take a lesser job and clear more without worrying about a student loan payment coming due.