CMake: use a custom linker

I want to setup a custom toolchain with cmake. I've set the compiler but I don't know how to set the linker. This error is reported because cmake try to use the compiler to link:

The C compiler "xgcc.exe" is not able to compile a simple test program.

Here there is a snippet of my toolchain file

# specify the cross compilerINCLUDE(CMakeForceCompiler)SET(CMAKE_C_COMPILER   xgcc.exe)SET(CMAKE_CXX_COMPILER xgcc.exe)#CMAKE_FORCE_C_COMPILER(xgcc.exe GNU)#CMAKE_FORCE_CXX_COMPILER(xgcc.exe GNU)

I've tried to force the compiler but the linker problem will not be solved.