[Therion] Need metapost wizard: new text label

Hi there, i need some new point symbol (text label). Its a simple text on white color within a box with rounded corners, like the attached image. My metapostskills are not good enough to get this to work... For now i would be happy to have such a user point symbol. It would be important that it scales well and react to xtherions direction setting. Optional it would be cool if the default symbol could show the current survey identifier of the nearest station in the scrap and maybe also the nearest next survey. But this information could also be maintained manually for now. Is there someone here for my rescue? :) Thanks in advance, Beni