From Gumstix User Wiki
1-wire functionality/module is turned off by default.
Based on this wiki resource and other discussion forums, it looks like nobody has succeeded to make it work till now. Please, contribute, if you did!
How It Works
U-Boot needs to be modified. Currently all the GPIO multiplexing for the Overo's is being done by the bootloader U-Boot, so the conventional way to modify the pin muxing is to edit overo.h and rebuild U-Boot.
You can also change the mux configuration from within Linux. One simple approach is to do it from userspace accessing /dev/mem. A program devmem2 is part of the omap3-console-image and will work. See the remuxing example below.
40 Pin Expansion Header
Pin 19 - gpio170
The HDQ/1-Wire output. Not used unless you explicitly enable the 1-wire module.
Output only - configured this way in the u-boot muxing
Enabling 1-wire module
GPIO Software for the Overo
Dave Hylands has written several software packages to facilitate GPIO programming on the Overos.
GPIO Event Driver allows multiple GPIO lines to be monitored from user-space.
User GPIO Driver is a reflection of the kernel's gpiolib API into user space.
Here is another article BeagleBoardPinMux talking about OMAP3 pin muxing.
Related pages on the old wiki: