Niall Douglas provides these notes:

The quick answer to this is: no.

The longer answer is that it can be patched to be so, but it's complex. You will need to add custom lock/unlock wrapping of every time your code enters Boost.Python (particularly every virtual function override) plus heavily modify boost/python/detail/invoke.hpp with custom unlock/lock wrapping of every time Boost.Python enters your code. You must furthermore take care to not unlock/lock when Boost.Python is invoking iterator changes via invoke.hpp.

There is a patched invoke.hpp posted on the C++-SIG mailing list archives and you can find a real implementation of all the machinery necessary to fully implement this in the TnFOX project at this SourceForge project location.