We did. First thing to do is find a local lender that will do them. Then let them help you with the application process. It's a great program for banks, because they get 50% of the loan and the government guarantees the loan, so they should be enthusiastic about helping you with it.
I have a 504 loan. They are great. 20 year fixed mortgage. The CDC fees are a bit expensive but worth it. No one gives 20 years fixed commercial mortgages. One of my friends just got a SBA 504 for a 25 unit motel at 3% interest for 20 years fixed (the 3% includes the CDC fees). 504 loans are currently at 2.99%.