I don't know of any websites but it is possible. A ceiling fan should be supported properly Either directly on a joist or on a brace between joist. New code requires a special box that has larger screws and/or a way of preventing them from falling out from vibrations. Home depot carries these boxes with braces that can be installed without going into the attic. This will require removing the old box which can be difficult if it has been used as a junction point for other devices which is usually the case. All wires will have to be removed from the existing box then reconnected in the new box. I do not recommend a novice do this on their own. What I suggest is to try to use the old box regardless of code. See if it already has support to the joists and if it does then use lock washers on the mounting screws to the box when installing the ceiling fan mount. If you do not have support, then you will need to go into the attic and support the box. My favorite method is to cut a 2x4 to the distance between the joist and nail both sides to the joist just above the box. Then i lag bolt the box to the newly installed board. This is much cheaper than buying some high fangled home depot ceiling fan brace kit and less tedious, even though it means a trip into the attic. Another thing, If you want the fan and lights switched seperately on the wall, then a new switchleg will have to be fished down the wall and ran to the box in the ceiling and you will once again have to go into the attic. When remodeling with electric devices anything is possible it just depends on what length you will go through to get it done. Good luck.