Is not possible:
Use GCC with kinetis K.
It's possible:
Use C++ with GCC
Use MQXLite with Kinetis K (don't work in all CPUs and some peripherals don't work if MQXLite enabled)
Use C++ with MQXLite
Seems it's not possible:
Use shared libraries with MQX and Freescale toolchain
Don't know:
Use shared libraries with GCC and MQXLite or MQX
I already did a test project using TWRK60F120M with PE, MQXLite and C++. If anyone need how to do this, let me know.