If SCSI disks are present in the system then it usually is better to build the mid level driver into the kernel. However if the SCSI subsystem is only being used periodically (e.g. to burn CD-Rs on an ATAPI CD writer) then building the mid level as a module is fine. The module load time options are the same as the driver's built in options:

scsi_logging_level=<n>
    where <n> is the logging level mask (0 for logging off)
max_scsi_luns=<n>
scsihosts=host0::host2