You can call any script from any other script. For instance, if you can run a script called fixSword.hsl in your current project by typing fixSword; at the command line, then you can also insert or nest this script in any other script. For example:
select LFHD LBHD RFHD RBHD;
fillGaps -rigid -all;
// nested script follows
You do not have to use the HSL extension when calling a script. However, the called script does have to be located in a directory specified in Script directories in the Shogun Post Preferences dialog box.