Sali - I don't think you 'l have to modify anything for the splint.... just buy clothing 2 sizes bigger, short sleeves. Put the affected side on first, then the other side and over the head. I would go with a fleece jacket 2 sizes larger as well. If you can't get the sleeve on, then you can just cut it open and apply some velcro or make some holes and use shoe strings....
-fran