Hi,
To compile WRF for LES simulations, you can either compile for real-data, or for an LES idealized case. If you're planning to use actual real data, you will compile the model the same as any other real-data compile (
see the steps here). If you're compiling the em_les case (idealized case), instead of issuing the command to compile the real case (./compile em_real >& compile.log), you will issue (./compile em_les >& compile.log).
You may find some of the documentation listed in
this FAQ to be useful.