It's possible to work the ISS digipeater with an HT and a duckie. I have done that a handful of times. A directional antenna - Arrow Yagi, Elk log periodic, or homebrew equivalents of these antennas - helps put your HT's transmit power to better use by sending your signal in one direction, instead of basically all directions.
Maybe you and I can work each other sometime. Use APRS messages, which your HT should support, and you can make exchanges with other stations through the ISS digipeater.