Diacritical marks

In KMail under SuSE 7.3, I am using a standard 101-key keyboard set up with English (US) and US-ascii in the Kmail setup. Frequently I need to use diacritical marks (Swedish and German). In Win98 it is easy (ALT+---). I can change the Keyboard to Swedish or German using YAST and get the characters I want but that is not convienent.. Can anyone give me the proper keystrokes and/or procedure to do this?? Have checked Unicode and Evertype to no avail. Regards, Bob