You're going to need a pretty high pass to hear them with those duckies, but it can be done. Better is a discone, nice and high - actually the best is the Arrow antenna or similar - one that can be pointed and track the ISS as it rises/falls from your perspective. They aren't cheap, but there are plans on the web for building similar antennas. Some folks also use 'Eggbeaters'...
You will also need to be able to tell when the ISS will be visible in your area. Not all passes are good ones - our SATCOM wiki has links to several satellite tracking programs, and note that from time to time, there are some tracking updates (called Keplerian Elements, after Johannes Kepler) you need to do from time to time...
SATCOM - The RadioReference Wiki
Get your tech license, and with the right gear, and if you happen to catch one of the astronauts on the air, you can talk to them. I've never had the pleasure - I have heard the packet beacon, but it's been years - but it's a real challenge to do. I know of one ham that did it with a 5/8 wave vertical from his car- no doubt it was a fairly high pass, so it can be done even with modest gear.
And not to go too far off topic, but at times the Kenwood can be reconfigured as a repeater - and that there's now more than one ham station on the ISS. Keep in mind that they have a busy schedule up there, but NASA does encourage them to play ham when they have the chance.
73 Mike