Anyone used a USB microscope to align cartridge?

Although we are 5 yrs down the line I agree with Stanwal. ;^)
The Graham is the easiest method I've ever used and the most easily re-checked (i.e. by putting it back on the jig any change in position due to applying the stylus guard or loosening of cartridge screws is immediately apparent - as I discovered recently!)
The only advice I would give is to be careful with self-induced parallax errors.
The Graham method is very comfortable and easy on the eyeballs with minimal risk of damaging the cart during install.

On the subject of parallax errors I would also suggest that using a 400X or 800X magnifier on a cart is not as straightforward as the casual purchaser might think. Ideally, the cart would be attached to a machined platten with the microscope locked on to it and with the capability of adjusting it to an exact measuring position. Since you really want the stylus to be standing upright on the LP at the time of measurement such accuracy isn't even remotely possible without a variety of angular errors occurring. Eyeballing cartridge vs microscope orthogonality isn't a reference point I would personally rely on.
Just my opinion...

Here some pictures with a Dynolite 220x

https://www.dropbox.com/s/49jq2eyqssnr43w/EMT%20JSD6%20Diamamond.jpg?dl=0

https://www.dropbox.com/s/kqe3cqruvtq128z/Diamant%20verdreht%20Skala.jpg?dl=0

https://www.dropbox.com/s/skw82l9yohw3pna/VTA%20Kleos.jpg?dl=0

https://www.dropbox.com/s/f6a9ow4gam58u3v/AT%20OC-9.jpg?dl=0

https://www.dropbox.com/s/wmokgjww3nxvyx5/AT-OC9%20Mikroskop%20Verrundung.jpg?dl=0

https://www.dropbox.com/s/c4mo6g2avtkbnin/Black_von%20seite%20220fach.jpg.jpg?dl=0

What is very important is a possibility to place the microscope good and to move it sensitive.

I have rebuilt a vernier height gauge.

https://www.dropbox.com/s/yvbpuz3hp3yt572/Dino%20Lite.jpg?dl=0

Great pictures ninetynine.

I have used a cheapish scope, a Veho 400x from amazon.
http://www.veho-world.com/main/shop_detail.aspx?article=40

Not as good as the Dynolite but does give decent results. Needs a lot of patience to get clear images

this is a photo of my Lyra at approx 91/92 degrees in my 4point arm which has adjustable VTA.

https://www.dropbox.com/s/hygrlyr7nm7ydsi/Atlas-92.5-degSmall.jpg?dl=0

It is a useful way of getting a ball park figure and yes there can be errors. Fremer gives step by step guide on his analog planet site.

After an approx initial set up with the microscope, I adjusted the SRA/VTA by ear. Then checked again with the scope, that is the image link above. I was reassured that the best sounding position correlated with the visual confirmation.

I use a mini oscilloscope and test tone LP to adjust the azimuth.

Great pictures Nine and Veho. From the microscopic view, how do you get the overlapping lines for SRA/VTA? Do you photoshop them in and then estimate the angle or does the microscope have a grid on it? Also, in looking at the digital microscopes some of them have a longer working distance which would seem to me to be a better option. Comments?

Thanks Lubachl.
I used Adobe illustrator as it gives a bit more control over the placement of lines, then printed out the image and measured the angle.

The veho is fairly cheap, I believe the dynolite has some software to enable the placement of measurement lines.

I had to remove the clear plastic cowl around the lens on the veho to be able to get the scope close enough to focus. I think this also necessary for the dynolite.

It is very fiddly to position the scope relative to the stylus to get a good image. Time and patience required in abundance. A longer working distance might well be an advantage.

Fremer on his analog planet site describes his methodology for using a usb scope.