If you run the package through a sql server agent job, within a step defined as Integration Services Package there is a tick box on the advanced properties to elect it to run as 32 bit - by default it will run under the type of install - if SQL install is 64bit it will run as 64bit unless this box is ticked.

If running from the command line the same applies but on this case a parameter is supplied to force to 32bit if running on a 64bit server.