Increase TMG persistent cookie lifetime.

Hi,

I know it is not safe but we need to increase the Persistent cookie lifetime on our TMG server more the 9999 minutes.
In TMG there is a build-in security that prevent me to configure more than 9999 minutes.
Is possible to get around this lock with some ‘hack’? Maybe a config file where you can change this maximum value? Or something else?

Thanks in advanced.

Johan