I found the location of a 'reverse' font for you.
Try http://www.fontspace.com/wa2ise/backwards.

I also understand you may be able to mirror print without this if your printer has mirror capabilities. Evidently many do, but mine doesn't. A web site out there suggests you just check into the advanced capabilities of your printer and if you see Mirror Print, you try that. Apparently lots of silk screeners need this function.

Good Luck.
m