In not sure if this is the most efficient way, but the way that I did it when I had this problem was to write the UIR out in text format (op[tion->save in text format) then manually edit out controls and attributes that do not exist in 6.0 (any trees, top x axis on graphs etc) and change the version to 6.0. Resave it and open it and walla it works. The nice thing about this also is that if you miss some attributes that dont belong it will tell you the offeneding attribute so you can just keep editing them out.