Archived: Solution is meanwhile available in Spring. No need for copy & paste code anymore.
An example how to replace (most) functionality of a SpringJUnit4ClassRunner by a JUnit TestRule as introduced in CoreMedia Minds Post
Mind that the rule copies some (and not all) behavior of the SpringJUnit4ClassRunner. So the normal restrictions for copy & paste code also applies to this solution.
Note: There is a more complete solution already waiting as Pull Request 222 for the spring-framework addressing this issue which is also described in SPR-7731.