Under windows, switch the text indicator to '\'-codes and enter "\B0" This should give you the degree symbol for most fonts (Arial, Courier, Tahoma, Times, etc.).
If you know the ASCII number of the symbol you want to use,just hold down the ALT-key and type in the ASCII-value using the numeric keypad of your keyboard.
In your case: ALT+248 (this is the ASCII-value on mine computer)