For RHD 250se coupe`/cabriolet, the original part number for the right side under dash cover was 111-680-65-17, but was changed to 000-983-22-91, which is a square meter of the actual material the original was made from. So for this one you'd need a template or original to go from. The material is still available.
For the left side under dash cover, the original part number for a RHD car was 111-680-56-17, but it too was changed to the 000-983-22-91. So again, you can get the material, but you'll have to have a template or an original to go by.
The pieces for LHD cars are still available new, and I want to say that the pieces for the RHD models could very well be inverses of the LHD pieces. If so, then you may be able to buy the LHD model pieces and use them as a template but the inverse of. Also, if you have air conditioning the left hand piece will have to be further modified, but only after the original shape is cut out.