I don't know what kind of keyboard you're typeing on, but if you have a standard American k/b, you can map a seldom used key to be
a Compose key.* I have an IBM model M k/b that has no Microsoft keys, so I made the right CTRL ky to be the Compose
key. You could use the right ALT key, or the right Microsoft key, if you have one. Then a combination of two keystrokes after--not simultaneous
with--the Compose key will produce the foreign characters, assuming your loaded fonts have them. (Most do.) I can type cañon, álamo.
¡Verdad! ¿Es bueno, no? (CMP !! or CMP ??) I can also type ß, ä, ö, ü (German characters) garçon, hôtel, (French orthography) più (Italian
accent) € £, ¢ and various other things. (½, ¼, ⅓, ¥, µ) The compose key is not the same as the Alt-Gr key. See: http://en.wikipedia.org/wiki/Compose_key
* Make compose key according to this url:http://fsymbols.com/keyboard/linux/compose/