Unfortunately, unless you have a PS3 to transfer it from you're out of luck on that one.
I thought you could directly down load it now. It's actually listed in Vita games you can find through Vita->PSP
Not on my Vita it isn't. The website also lists it as playable on PSP, but not Vita. This is in the US, maybe in Europe it's different? If it's confirmed compatible I hope it becomes available soon, this is one I really want.