There are potentially two ways of doing this. If you are using the latest Beta version, you can add the #CRLF# variable to the substitutions to create line breaks, so each month would look like this: "September":"SEP#CRLF$TEMBER". You would then need to make sure that the H of your string meters is sufficiently large to accommodate the two lines.
If you are not using the latest Beta version, you will need to duplicate the measure that is reading the month, and then modify the substitutions so that the first measure has the first part of the word (the "SEP") and the second measure has the second part (the "TEMBER"). Then you can either use two string meters to display the measures one on top of the other.
