No....this is (or it should be if it isn't) a user-initiated thing.
It wouldn't be very good for a browser's "security" if a web site's code
could overwrite a setting the user has in place i.e. cookies off and turn
them on.
(That seems to be what you're asking, i.e.: "is there a way to instruct the
user's browser to enable cookies?")
The only way is to notify the user the site uses cookies; but it is
ultimately the user's decision to enable them.