You probably know this already but incase you don't....
You should be able to do it on most laptops, usually the Numpad keys work by holding
[fn]+ALT+ (code)
Sometimes the (code) keys are not the actual number but are letter keys.
Anyway, have a look at the link, there are codes for those super-cool German Ü, ß as well as those goofy little French Ç
(maybe Rafiki can split this?)