Found my answer here:
Which recommended:
uicontrol('Style','list', 'Position',[10,10,70,70], 'String', ...
{'<HTML><FONT color="red">Hello</Font></html>', 'world', ...
'<html><font style="font-family:impact;color:green"><i>What a', ...
'<Html><FONT color="blue" face="Comic Sans MS">nice day!</font>'});