field double entry verification (e.g. password)

I want to have user enter a "password" and "confirm password" field (like email works) and ensure a 6 to 20 character entry. This is not for a Wordpress user account - data will be exported daily to set up in another system.

It would be nice if I could use the "advanced field / email" field and it allowed the prompts to change but I don't see how.

Or if in conditional logic, the right side of the compare could be "another field" instead of a "value" (like "password" "is not" "{confirm password}" - then I could have another field that was really an error message and only showed up if the two fields were not equal.

Or can I embed custom code at time of "submit" (and where?)

Thanks for any help for a "gravity forms" newbie - this is a cool product.

Regards. John

Thanks Chris. That's perfect. Except one small point as a GF newbie. I have programmed php before but not in a gravity form context. Can you tell me (or point me to a documentation link) as to where I put the <?php ..... } programming in your example? Thanks.