Yes, this is possible, though it needs someone in control of the
opendataday.org DNS to set a CNAME record to the hostname of your choice.
In our case, we gave the
opendataday.org team an intermediate hostname that someone on the DC organizing team controls ("
opendata.konklone.com") and then we set a CNAME for *that* record to point to our actual hosting service (currently GitHub Pages).
By using an intermediate hostname we control, we can change hosts without having to go back to the
opendataday.org team each time, by changing what the intermediate points to ourselves. We have changed hosts once already, it used to be Amazon.
I believe OKFN staff control the
opendataday.org domain, so you would need to petition Rufus or someone else there, I think.
-- Eric