You can apply the deformation map stored in that file using svreg_apply_map.sh script that should be in <BrainSuite18a>svreg/bin folder.
The usage is described here.
#13 here http://brainsuite.org/processing/svreg/svreg_modules/
The map in svreg is stored in a slightly different format than the one in fnirt, so svreg_apply_map shoudl be used for the svreg map and FSL’s function for applying maps from fnirt.