Not having looked yet at the mentioned website I just want to mention that I am using xterm to create up to 75 additional characters on a US set keyboard using the alt and alt-shift keys: ° ½ ã ä å á å ³ ´ ç ô ù õ just typed randomly as an example. Unfortunatly this feature is lost with all other terminals I have tried.
To find which character to look for I made a table with all the 75 possibilies, printed it out and pasted on a card board. From xtern I copy and paste.
® ¼ ¾