How can I format a specific cell using the Ruby Spreadsheet library?

Formatting a column or row seems to be no problem. I've poked around the documentation a bunch, did some searches, and looked through the "methods" result on some spreadsheet objects and I can't figure out how to format a specific cell. Has anyone done this?

The Spreadsheet library is here: http://spreadsheet.rubyforge.org/ http://spreadsheet.rubyforge.org/GUIDE_txt.html