A general FYI asking the same question again that you previously posted which is also only 4 threads below in the same forum is not good form per se. I'm not the moderator, but it's best to keep your question to one thread. You aren't going to get a magically different answer.
I recommend that you ask this question on the Google developers email list/google group, but first search for an existing email/answer as it's likely there with an authoritative answer. If you don't find the answer already then ask this question there and add attn Diane Hackborn in the subject (if you wanna be direct and presumably slightly annoying about it!). She is an Android framework engineer and will tell you definitively that it is not supported.
I highly doubt this functionality is accessible. It's a phone! 911 / emergency support must work no matter what and no 3rd party service or app will be allowed to modify absolutely crucial functioning of phone service. It'd suck for a rogue app/service to hang up programmatically emergency calls.
Founder & Principal Architect; EGR Software LLC