I already got help from you guys to get started with the Indico importer. I also got help to add some custom code (presave hook).
However, I realize that what I would need is a way to manually trigger the import, from the admin interface somehow.
How can I deploy some code to do that?
Once you have enabled the Indico Feeds module you have to create a Feed to pull events from your categories. Go to Content, click on the Feeds tab and create a Feed of Indico Feed type. Add your category(ies) ID(s), select the from and to dates to pull and Save.
You can set up the import interval in Structure->Feed types->Indico feed
Once the import will start the presave hook will execute the code for each one of the imported events.
You can also trigger the import manually by going to Content, Feed tab and click the import button next to your feed. There is a drop down list with options there.