You'd be better off rethinking the mail delivery. Is there an absolute need to keep using an outdated, bandwidth hogging feature like a POP3 connector?
josephdavis is correct - other third party solutions would do the job better. The one I have used a lot is the one included in GFI's Mail Essentials. That connector let's you set intervals as low as 1 minute. But that's still 59 seconds longer than if you just had mail delivered directly to your server (and uses much less bandwidth, too). Less administration as well.
Pat Richard, MCSE MCSA:Messaging CNA
Microsoft Exchange MVP