keyboard problem with 266MHz iMac

[Carl Weitz]

The modifier keys don't work for my old iMac /w 266MHz G3 CPU.  After 
fixing the problems with the modelines to get xfree86 running and 
changing XkbLayout to de_DE to get german umlauts, I don't know how to 
get chars like @{}[]|~\ hidden somewhere on the third keyboard level. 
With MacOS I would get those chars with the Alt or option modifier keys, 
but with Debian those keys don't work.