Do you have an Edison or a Galileo? The hardware modification you mention is for the Galileo.
Thanks for pointing this out!
Mine is Edison, howeverI think the discussion applies to both Galileo and Edison. I even contacted DinoT (who started the discussion) and he confirmed this.
After doing some research I found an analog humidity sensor, please take a look at its datasheet: http://sensing.honeywell.com/honeywell-sensing-hih4030-4031%20series-product-sheet-009021-4-en.pdf?name=HIH-4031-001. I think this sensor is what you are looking for because it has an analog output voltage so you can plug it to an analog input and read its value.
I hope you find this sensor useful for your project.
Thanks for the reply! This is exactly what I was looking for. I just got one and tested it. It worked perfectly.
All the best,