Using angular-cli at the command line, I executed:
ng set defaults.styleExt styl
to set the default styling to Stylus and I got this response:<
ng config projects.PROJECT_NAME.schematics.@schematics/angular:component '{ styleext: "scss"}'
for a specific project or for the default across all projects
ng config schematics.@schematics/angular:component '{ styleext: "scss"}'