Some posters here say the ticket machines at CDG work with non-chip CCs; others say they don't. Otherwise you can go to the counter and buy them from an agent with either euros or a credit/debit card with or without chip.
We had four U.S. credit cards (without chips) rejected by the machines as unreadable (error message: "carte non lue") last week, before giving up and queuing at the windows. All four cards were known to be good; three of them have been used successfully in France since. The agent confirmed that the machines require a chipped card but the readers used at staffed windows do not.