Given the popularity of this hack, I am surprised it is not supported yet. Better still, the ez-ipupdate in the V6 Beta won't even support it. Starting the DYNDNS service with the hack yields:
:/var/mdw/scripts # ./dyndns restart
Shutting down Ez-IPupdate:1
Starting Ez-IPupdate:unknown service type: dyndns-custom
try one of: ezip, pgpow, dhs, dyndns, dyndns-static, ods, tzo, gnudip, easydns, justlinux, dyns, hn, zoneedit
[:(]
Worked so well in 5.2... [:S]