Residence Requirements
Any non-European Union citizen planning to stay within the Schengen area for more than 90 days will need to apply for a residence permit.
In law 3386 of 23 August 2005, the Greek government clarified the residence situation for members of Foreign Archaeological Schools and Institutes such as CIG. Thus, the application process for Canadian Institute members has now been simplified into a two-step process:

Before leaving Canada, you need to obtain a special visa from a Greek consulate
Requirements for Visa

Upon arrival in Greece, you need to apply for a residence permit
Requirements for Residence Permit

Relevant parts of Law 3386/2005 (in Greek)

Athens: Bookshops for Classics-Archaeology
Andromeda Books
Archaeological Receipts Fund
Archaeological Society of Athens

Athens: Greek language courses
Athens Centre
Hellenic American Union
Institut Français d’Athènes

Greece: Media
Kathimerini English Edition
Odyssey magazine

Greece: Cultural Information (in Greek)
Athens Voice