Sorry for the time without answer...
Well... in bold: [c=4][b ]Joe[/b ][/c] (of course, without spaces), WLM accepts it.... And you have a Bold Red "Joe"....
About longer nicknames (if you need to put many codes and a bigger nickname) I think that will be a limitation, as Plus! needs "complete" codes: [c=4] and [/c], for example to make the colors and others opitions you want..... I don't know if it's possible to extend nicknames lenght....