This is sad, because it's kinda railclone job. :'(
My method is to generate walls with railclone, convert to edit poly, assign ID's, then detach all elements(scripts), then apply UVW map using pivot points, then attach them if necessary, so it's waste of time.
It wouldn't a problem if railclone could apply RWC mapping to each element and correct ID and without shifting the map on each element, because I can adjust texture accordingly.
Unfortunately I couldn't find workaround with Corona renderer functionality.