I still have mine from radioshack too, used it for years. Radio shack doesn't have them any more, but THIS PLACE has what you need
Yup, i had one of these for a long time on my non-pro CH game-port pedals. The pedal are about 10 years old now, and the converter got about 6 years of use before it started crapping out - not bad really. The pedals are still mint. For a quick and easy solution those adapters work pretty well. They have a 4-way mode switch selecting 4 different stick emulations/modes. I think i used the 4-axis, 4 button mode (mode 1 or 2 i think). Windows thought it was a 4-axis, 4 button stick, and so did AH2. But the AH2 mapper lets you pick the rotation axis alone and ignore the rest. Just map it to analog rudder, and you're away.
If you have the non-pro version, you will only get the one axis (with "plane" mode set on the rudders) - this is what i had. If you have the pro version, i know there is a way to get the toe-brakes working as well, and i think it has something to do with plugging the bypass gameport cable back onto the main plug creating a loop of sorts - i saw it on ebay, someone was selling their pro pedals on a adapter and did that to get theirs fully working with toe brakes, i've since seen someone else mention something similar somewhere else. Experiement a bit.
If you're handy with a soldering gun and have some electronics knowledge, then you could try rewiring it with one of these
http://www.lbodnar.dsl.pipex.com/joystick/ This is what i have just recently done. Works brilliantly and much smoother too.