Sure it can be done. You'll only be changing the most complexe function of the most complicated applications that Notes has. No problem. ;-)
The ugly hack would be to open the Calendar Entry form and simply adjust the Default Value of the field EnterBlindCopyTo to add the values you need.
A slightly better version of this would be to define a list (in a Profile Document) of users to add and have the Default Value get the list contents. In that way, if the list is empty, you have in effect changed nothing.
The next step would be to imagine that said list will probably have to change following which user group is creating a meeting. In that case, it might be better to create a database with a view that lists people names. Users accessing the db can be assigned a role, and docs can be set to be read only by one role. So the Default Value can now do a lookup of the view and pull a list of names depending on who has what access.
I can't think of anything better right now.
Pascal.