There is currently no API to do account creation
(
https://www.mediawiki.org/wiki/API:Account_creation is a draft, and
IIRC there is nobody actively working on it). There was a GSoC
student working on it last year
(
https://www.mediawiki.org/wiki/Extension:SignupAPI) but I don't think
that's in any state to be deployed soon.
--
Yuvi Panda T
http://yuvi.in/blog