I went to a seminar on this topic 3 years ago. The essence of it was that it was possible if you use an Custodian like the firm who put on the seminar and used a non-recourse loan like the one I have have linked below.
There were other restrictions like not using the property yourself as a second home.also, all rentals had to be arm lengths transactions and not made to family members.
When I researched this, I found that there were IRS cases where IRA holders were penalized when they made withdrawals to purchase rental property. I discussed this with my accountant, he pointed out that the advice that the IRS get you over the telephone is not binding in this matter and he would advise against it.
So, I suspect that it may be possible but also not without some risk. - Sat Oct 11 2008, 14:44