It would be helpful to know where you are at, and what types of systems are in place. Not everybody goes by "grades" in general, as far as I understand it. My perspective is from somebody who didn't go through all of that myself (but did study in University), and who teaches but does not currently push students to be documentedly involved pianistically. Each school *should* give some kind of indication on what would be expected for an audition, and ideally, the audition is the big part of what weighs into the decision regarding entrance and acceptance.
But, grades and other documentation don't hurt and this is why - it is a way for somebody who doesn't know you to gain some sense of your dedication to what you do. This is a concept I've had some grasp on, but recently in the last few months, especially, have been looking at from a new and different perspective. From an "outsiders" viewpoint, if people are going to invest in you, they want to see that you are worth the investment, and that's probably a plain truth. Keep in mind that this isn't addressing the inner viewpoint and psychology of the person themselves, necessarily! Just because you don't have documented study, doesn't mean you aren't serious about what you do (there are an array of reasons for not having that in place, and I would *think* this is at least partially comprehensible by people who are in the business with their soul!) and, in fact, just because a person does have those in place doesn't necessarily mean they are serious about what they do. I think there is some wiggle room, as you can't actually go back in time and change anything; you can only be who and what you are now and today and that's exactly who and what you have to be able to be no matter what.
I can't say that I know how quickly you could get that stuff in place if you need it to be there, but I think it's possible to test into whatever grade you might be at now ... or test through several others in one sitting, etc.. It would be very good to get into contact with a vibrant teacher who is knowledgeable about these things and could help steer you in the right directions based on actually knowing where you are at in relation to what may be required.