It can be done at the government‘s state funerals and national commemorations website at www.commemoration.gc.ca.
A government statement says the condolence messages will be printed and sent to Flaherty‘s family.
The government has also made a book of condolences available in the Hall of Honour on Parliament Hill.
Flaherty died Thursday at age 64 of a reported heart attack.
A state funeral for Flaherty will be held Wednesday in Toronto.