No it is not easily possible, Aruba Central is not really MSP or IT Support Provider enabled at all and I would to expect it to be any time soon. There is what they call MSP mode but it is misnamed. Their "MSP" mode is really a fully hardware managed solution where the managing IT company owns and leases out hardware and licenses to clients. So their MSP mode is not really for MSPs at all, there is no ability to centrally manage/monitor/delegate permissions to the client network if the client owns their own equipment and licenses. We have spoken with HP about this several times and they don't get it. As far as I have been advised; to manage as a support provider you need to have every one of your clients manually delegate access to every one of your technicians, unless you want to use a shared account which is not great from a security standpoint.
I don't know the specifics or how granular you can get but If you want to grant the customer limited access I think it can now sort of be done with Greenlake. You need to create/use the original master account using a client e-mail addresses. Delegate Greenlake full administrator access to one of your IT support accounts. Then you can create a security policy with some level of limited access. I think that is done in Greenlake not Central. Invite a different client e-mail account access to Greenlake as a member of the limited security policy group.
Please leave your feedback with HP; if enough IT providers complain maybe they will eventually build a better solution for MSP/IT support providers.