James Boll, a mortgage broker at Paradigm Mortgage Associates, says he is the only loan officer in Jacksonville, Fla. who can take his laptop into a Realtor's office to deliver on-the-spot loan approval that will stick.His secret? Freddie Mac's Loan Prospector on the Internet.That means loan officers working with buyers do not have to wait days or weeks before giving assurance to real estate agents, builders, buyers and sellers that the mortgage-financing leg of a transaction will not collapse.