[syslog-ng] stunnel through elb.. need packets sent semi-frequently

I'm using stunnel to pass some data through an Amazon ELB. Unfortunately, there are times when the session times out due to packets not passing for 60 seconds (an amazon ELB timeout). I'm wondering whether theres some way I can configure stunnel itself to pass some whitespaces or something back and forth every few seconds to make sure the session stays open and live? (and yes, I'm posing the same question to the app developer who's ap we're passing through.. but I'm looking at both avenues.. )