Hi,
Just source your mricron folder in your shell file (e.g. .bash_profle)

For example if your mricron folder is ins /usr/abin/, you would add the following to your .bash_profle in your home directory.

MRICRONDIR=/usr/abin/mricron
PATH=${MRICRONDIR}:${PATH}
export MRICRONDIR PATH

Alternatively, you could just type the whole path into the script.
However, you would have to edit your script for other computers where the location of mricron differs.
For example.

/usr/abin/mricron/dcm2nii

Hope this helps.