on a shared account you will be unable to have an official NS record that makes the glue, it is only supported on the reseller accounts in the E.Manager Server Aliases. That being said, we have some shared clients doing this without any issue. Just when you go to a tool like dnsreport it will give the nameserver custom then a (no glue) message to the side.
I’ve then gone to ukreg when my domains are registered and changed the name servers to point as above. According to ukreg, to make my glue records i have to enter the name servers as: ns1.mydomain.co.uk[full stop][space][ipAddress]