Extern, how to import a function and rename it ?

This works:

extern "Win32"
 Function RegisterClassExA(pcWndClassEx:Byte Ptr) 
endextern

This does not work and results in the compile error above:

Extern "win32"
 Function RegisterClassLALALALALALAL(lpWndClass:Byte Ptr) = "RegisterClassExA"
end extern

( renaming the somewhere predefined RegistarClassExA from user32.dll is not possible, at least not on this way )