Microsoft may have only just announced Windows Phone 8 Update 3, but the company plans to start delivering it to developers later today. After over a year in the making, Microsoft is finally launching its Windows Phone Preview for developers. The program will provide registered developers with early access to Windows Phone 8 updates, bypassing the complex and lengthy carrier testing process. Microsoft is specifically targeting developers with this program, but for $19 a year any Windows Phone 8 user can sign up and get early access to updates. Even registered Windows Phone App Studio developers will be able to get early access.
by the way,you can register for a free developer account that has a sideload limit of 2. this should work as well.