You can't use the symbol font, unfortunately. You'll need to use a "real" font and enter the text as unicode values. Unicode is just a standard representation of characters for all languages. (Feel free to google "Greek unicode")
One way is to find the text (Greek unicode) online and copy-paste into Excel/Word. This is how I get my Chinese into Excel for example... copy-pasting from web sources.
You can also try this website to convert symbol font text into unicode:
http://www.snible.org/greek/symb2uni.htmlErnie