Por ejemplo bajé la fuente HAND OF SEAN:
http://www.dafont.com/es/hand-of-sean.font

y quiero usar la carita, como saber que tecla pulsar para que aparezca al momento de escribir.
Gracias de antemano!

You can use "µ" for example: http://www.dafont.com/es/hand-of-sean.font?text=%B5

That solution only works in the first version of the font where many not so common glyphs were not available but there as a undefined character. The latest updates of Hand of Sean do have these characters so Fred's trick does not work with with those versions.

Thanks a lot!!!!