I am thinking this standard through as we speak. I understand the standard, but like any other standard of proof you have to establish it by credible evidence. Since homosexual sex is not normally conducted in public, it would seem very difficult to do more than place the applicant under oath and ask him or her to swear that he or she meets the standards. If there is something that I have not thought of pleases enlighten me.
In practice the standard is going to be ask but don't tell. If a homosexual does not publicly identify and does not support the gay agenda then it would seem to me that he would qualify.
I don't know if you've read some of the voluminous threads lately about this document, but it's been hashed out pretty well. People who know about such things; for instance, how seminarians are vetted, tested, and so on - think this will screen most out.
To me, the important part is will current priests and bishops who are homosexual get swept out? That needs to happen at least as much as no new ones.