If you setup a simple case using CTSM, e.g.,
./create_newcase --case ctsm51_ctsm51d118_1deg_GSWP3V1_soilmoisturestreams_2000 --compset I2000Clm51BgcCrop --res f09_g17 --run-unsupported
cd ctsm51_ctsm51d118_1deg_GSWP3V1_soilmoisturestreams_2000
./case.setup
Then add "use_soil_moisture_streams = .true." in user_nl_clm
./preview_namelists
The soil moisture stream file should appear in CaseDocs/lnd_in:
&soil_moisture_streams
soilm_offset = 0
soilm_tintalgo = 'linear'
stream_fldfilename_soilm = '/glade/p/cesmdata/cseg/inputdata/lnd/clm2/prescribed_data/LFMIP-pdLC-SST.H2OSOI.0.9x1.25.20levsoi.natveg.climo1980-2014.MONS_c190709.nc'
stream_year_first_soilm = 1997
stream_year_last_soilm = 1997