With utf8 off, I am able to display a bullet character with the command: t “\xb7” 100 100. Is there a way for me to display that same character when I have utf8 on?

You need to use the UTF-8 format of the character. For conversion between Unicode and UTF-8, see http://www.utf8-chartable.de/. In your case, the bullet character 0xB7 is c2 b7, so the text command would be:

utf8 on
t “\xc2\xb7” 100 100

Here’s a handy online conversion utility: http://www.ltg.ed.ac.uk/~richard/utf-8.cgi?input=b7&mode=hex

There are probably formulas to work these out in your application as well. Here is more detail than you might want: http://en.wikipedia.org/wiki/UTF-8