Your requirement seems quite function specific, and as such I would suggest you also post to the HCM forum as there could be people doing the same thing there.
Most of the packaged integrations are based around moving and sync-ing data between systems periodically, whereas I think you want a live invocation, such as the public WebServices might offer. As such please review content on http://fusionappsoer.oracle.com where you'll find all those listed with lots of supporting material as well.
Hope this gets you going in the right direction.
Oracle Developer Relations