The UV/IR filter is not an alternative to permanent camera modification. It is to colour correct a camera that has been modified so you can use it as though it is unmodified for "normal" photography.
Camera modification involves removing the UV/IR sensor filter that comes with your camera and replacing it with clear glass or a different filter to allow more of the IR spectrum light onto your sensor. This makes normal photos look reddish. The clip UV/IR filter corrects that red colour cast by performing as the Canon-factory filter did before it was removed.
I don't think this is correct. I do not believe that particular clip in filter corrects a modified camera. I think it's just a normal IR filter. As far as I know there are only 2 filters to correct a modified camera, one is from hutech (VLC-FF) and the other is an x-nite from maxmax.com.