Hoghead, the headlamp mod was made by Silviron. It is a modified Rayovac 'Adult' 4AA headlamp, the was rewired for 3 volt series/parallel, and the front was butchered, then a stub was used for mounting the Arc LS head.
With the upcoming LS4, I am thinking of a headlamp mounting system for that. It would be a bracket the the light is inserted into and clamped. This could be mounted to either a PT headlamp Replacement strap (includes base plate), or to a blade mount. Unfortunately, I have neither the tools nor skills to do this.
Even current model Arc LSes could be mounted this way (123 pack aka TSP-123).