You can use certapp to add new certificates
to an already existing certificate store.
The following example shows
the generation of a software install (SWI) certificate store file, new_swicertstore.dat.
This file is generated by augmenting the SWI certificate store represented
by swicertstore.dat with certificate entries specified in extra_certs.txt.
>
certapp --bswicertstore=swicertstore.dat --hswicertstore=extra_certs.txt --out
--bswicertstore=new_swicertstore.dat