I would like to add TLSA records. It seems you can only add records of pre-defined types. But there are numerous types not supported here. You could ease life for everybody to allow for a generic form that allows to add a custom type (by specifying the record in hex notation for example)
The only way I know of "adding" an unknown type is to declare HE's name servers as secondary, and add the record in your primary name server (elsewhere, and running DNS software which supports your desired RRtype).
TLSA records should only be served for DNSSEC enabled zones. Unfortunately, the DNS slave service doesn't support DNSSEC just yet, but it's apparently on the roadmap.