After much work, I have finally managed it.
A hamlet, the only settlement of this particular Elven civ, contains the Queen and her husband (who's the Princess, I think. I know, it's wierd. I dunno why.), and their offspring.
Oh, and lots of angry elves.
Well, it might still work.
Let the Elf Farm begin!
EDIT: Attempted an embark, and had to quit, misaligned it. Second time I managed to encompass the ENTIRE hamlet!
There's the Queen, Princess, Druid and Acolyte, and a group of children, friendly. All the rest are hostile. I've walled the dwarves in a small area around the wagon and began a (pretty messy) but adequate fort in the dirt layers. Unfortunately, it's a cold area, will be frozen and snowy a lot of the year, and has an aquifer. I may attempt to break through the aquifer by exposing it to the freezing surface.
Plan:
Break through aquifer. Begin fort proper.
Set up adequate defences.
Lure in entire 'hostile' elven population, cage and capture.
Herd (somehow) the royal family into their own (purposeless but amusing) royal rooms.
Build a standard dwarven fort.
Attempt to breed a line of elves (SOMEHOW) and see if they ever outbreed the dwarves! Should be amusing.