Originally Posted by RickJ

If you want to go straight from the typical date of 5/23/2011 (23 May 2011, May 23 2011) you could go with this:

2011年5月23日

BUT: Chinese dates are not like our dates.

My recommendation would be to speak to a local tattoo artist who does Chinese stuff and ask him (or her) what the best characters would be to do to represent the date that you want.