Similar questions come up quite often but so far in most cases it turned out that manual rotation in 3D view had not been a good solution anyway, so we did not end up investing a lot of time into improving the transform widget. It is true then if you could set the center of rotation and axes directions more easily then it would make accurate orientation somewhat more feasible (we have an open issue for this). But there are always much better solutions than free translation/rotation in 3D, because that is inherently a very tedious, iterative process.
If you describe what task you are trying to solve then we can give advice what tools you may consider.