My Unholy Scion Needs More HD

[Wombles]

I am going to be playing as an unholy scion with the base race of rabbit, There is a really cool table to spell like abilities that you get based on you HD.
We are going to be starting at level 6, so with 1 rabbit RHD and 5 LA what are the ways I can boost my effective HD to use the cool abilities that Unholy Scion gives me?

I know bards can Inspire greatness for some Temp HD, and the dusk giant infinite HD trick is a step to far into the cheese factory and after that Im not really sure what, if any, options are out there for bonus HD.

I was considering convincing another player to be a druid so i could be their animal companion, but Unholy scion changes my type to outsider so I don't think that will actually work.