how to grab a head count from boss?

our group has a head count. Big boss has already said in group meeting that this head count will support my projects. I am the only one has two projects and really strained resources here. The vacancy is in my direct superviser's group. His plan is to hire a person reporting to him but supporting my projects. I have told him that my main interests and future goal are not in his arena or group. so this may be his opportunity to find someone that could replace me in this job function. My question is how I can grab this head count before it is going to him. Or just forget about it.