Hi CL,
The special screws some watches use can absolutely be worked around by any decent watchmaker (which is certainly the point: decent watchmaker). I imagine the largest concerns with the Antiqua would be the specific knowledge/experience of the decasing and casing procedures and perhaps special movment holders required for same.
I also imagine most watchmakers skilled enough to perhaps pull it off would be unwilling to use a customer's watch as a proving ground to attempt to do so under normal circumstances. The possibility of damaging a component (hands, dial or case part especially) that is Janvier made simply due to inexperience with the model (as opposed to lack of skill) would be ever present and leave one with the need to manufacture something with great time investment as a best case scenario.
You'd have a much better time finding someone who absolutely should NOT be working on it offering to try than you would of finding someone who is genuinely equipped to do so. Great skill is generally only gained alongside a modicum of wisdom and prudence thankfully. 
_john