Adding a GJ kneelever to a Rodolphe /Ajouter un genou switch à mon Rodolphe

Hi there

I want to add a kneelever for GJ on my Rodolphe who has only a GJ knob .
Does anyone has a good advice, not ''DON"T DO THAT"!!~, but a nice drawing of a neat modification or a drawing of a Rodolphe who has already a kneelever for GJ ?
Many Thanks

Jos Vlietstra