unicode shortcuts

[Piers Kelly]

Hello,

I've recently shifted from PC to Mac.

On the PC I was able to use handy little alt codes to bring up IPA
characters and common orthographic symbols like á or ¡.

Alternatively I could type a four digit unicode figure onto the screen
and then type ALT-X to bring up the character I was looking for.

Does anyone know how this sort of thing is done on Mac OS X? I have
defined the keyboard style as Input Unicode Hex but with no luck.

Any clues appreciated,

Piers