I contacted ESPN. Apparently a slow draft is not possible because draft room's are only available for 24hr's. Here is there response.
Thank you for playing ESPN Fantasy Baseball.
I apologize for any confusion this may have caused. Unfortunately, we do not offer a slow draft option within our Fantasy Baseball system settings. There will not be a way for you, as League Manager, to set the draft availability for more than 24 hours. Our system settings will simply not allow this to occur. I will pass your comments along as a suggestion to our Fantasy Baseball department.
Draft times show up as they become available. As the season draws closer it becomes harder to a reserve draft time because there is a limit to the number of leagues that can draft at one time.
There is no guarantee that a specific draft time will become available, although it may happen due to leagues cancelling or changing their draft time.
We recommend that you select a time closest to your preferred draft time. If you wait for a time to become available, the available slots will continue to fill up. If you wait too long, your league may have to draft after the season start.
We will not "bump" another league who has reserved a draft time to accommodate other draft requests.
For live assistance with this or any other issue, please call Customer Care at 1-888-549-3776 (ESPN) between 8:00 a.m. and 1:00 a.m. EST.
ESPN.com Customer Care