You have to have a mac to create mac applications.

It is possible to create Symbian applications on windows because Windows is the only platform that is supported by the Symbian SDK.

The Symbian SDK comes with a cross compiler that runs on windows. You would have to have a cross compiler for mac. Although it is technically possible to create such a compiler, no one created such a compiler with a proper installer package. Cross compiling GCC is an advanced topic and it is probably cheaper to by a bunch of macs.