How to manually enable ipv6 on cpsrvd for dnsonly

I want to be able to browse to [my.ip.v6.address]:2087 and access the whm interface. However, in dnsonly, there is no tweak settings to enable listening on ipv6. I have manually changed the cpanel.config file with ipv6_listen=1 and rebooted, but that doesn't actually seem to cause cpsrvd to listen on ipv6. Searching, I have found similar requests regarding dnsonly, but these results have only revealed how to make bind/named listen on ipv6, not the whm interface. Can anyone tell me how to manually enable whm to listen on ipv6? Thank you.