Bouncy Castle elliptic curve from explicit parameters (E-521)
In order to do this, first convert the Edwards curve to Montgomery form, then to Weierstrass form, per this thread.

But, as the above thread explains, as well as CodesInChaos' comment, this will result in poor performance.

Thanks to CodesInChaos for pointing me in the right direction despite the stupid question.

Also see:


Elliptic Curves of different forms
http://samuelkerr.com/?p=431 which has a nice Python script for going from Montgomery to Weierstrass