1. Make sure you have “Tracking URLs” feature turned on in Yahoo!. Go to “Administration” tab “Tracking URLs” to enable it

2. Make mass URL updates in your Yahoo! account to: a. Remove all keyword level URLs; leave only ad-level URLs; b. Append the appropriate keyword parameters.

3. Done. Yahoo! will dynamically populate corresponding {OVKEY} parameters with the right values and Google Analytics should recognize and read them. source