The Cats Eye is clearly visible in my Back yard in Sacramento City without any problems at 90x using my C11 and 31 Nagler.
Its also easily found with my C6 Sct, also in my back yard.
As others have said, it should look like a puffy star, larger then anything else in the field of view you would have.
Just pan around very slowly in the area you are looking for and it should be visible with no problem. It takes magnification well but I'd not increase the magnification too much till you recognize it.
Use the other stars from Draco to get your bearings but with a 10" dob, you wont have any problem seeing it because you have plenty of aperture. Even with the moon in the sky, it should be visible.
You don't need a filter to see it, not with 10" of aperture. Just pan the skies very very slowly and notice what comes into your field of view.
Tried to see the Cat's eye nebula for about 4 nights this week with my 10" Dob.
And one of those nights I was at our star-gazing site belonging to the local club.
But no joy.
Its magnitude is 8.3 with a surface brightness of 5.5
I know I'm looking in the right place because I've almost got the surrounding star patterns memorized.
The highest mag I tried was 80x and I'm not sure with that it would even be visible.
I'm guessing the skies here are just not dark enough.