Yeah I did it with the help of this site!
The steps are:
1. Download the update from here.
2. Rename the file to update.zip. Note that if you’re using Windows, just rename it to “update” (no quotes, of course) because it’s already a zipped file.
3. Copy the update.zip file onto your microSD card.
4. With your Nexus One off, hold down the trackball and press the power button.
5. You’ll be booted into a white screen with three Android robots on skateboards. Select “Bootloader.”
6. On the next screen, select “Recovery.”
7. Your phone will reboot, giving you a picture of the Android robot and an exclamation point inside a triangle.
8. Now press the power button and volume up button at the same time. It could take a couple of tries.
9. Now (using the trackball this time) choose “Apply sdcard:update.zip” and let things run their course.
I did not intend to root it now. If you want, you can follow this steps:
# f you’re coming from stock and want to root, then follow steps above and then apply this update from Cyanogen.
# Or, if you’re coming from an already rooted rom/recovery, just apply this update from Paul O’Brien