Well the simplest solution is to grab ACT, which has been updated for 3.0, and autoattack a dummy.
Your crit rate is the same whether you are using weaponskills or autoattacks, so afk at the dummy for 10-20-30 minutes, that will get you several hundred if not a thousand hits.
And ACT will automatically tell you what your crit % is.

If you are looking for the crit damage bonus as well, then sort the data in ACT by whether the attack crit or not, copy it into Excel, average the 2 sets, and divide the results to get a sense of the crit bonus. Again this is best with 500-1000 data points.