I am getting a few leaks in the push rod tubes.

I bought some Viton O-Rings tho replace the old ones.

Can this be done with the engine in the car? With the exhaust on the car?

If anybody has done this, has tricks, or a technique that works, please share.

Thank you in advance.

Yes you can, but likely need to remove some of the exhaust tubes, then remove valve covers, then you have to remove the rocker arms (be prepared to reset the valves when this is all done).
Pull out all of the pushrods (label them, try not to mix them up) - you may not be able to get every one all the way out with the tubes still in place.

Then with softened pliers, grab the pushrod tube from underneath the cyls.
Push/pull and wiggle towards the head and it will pop out of the hole in the case and the head.
You can remove most of the tubes out through the head, a couple will hit the suspension ear.

I was told recently on this forum that once you pop the tube loose, you can tilt the engine side down and pull the tube all the way out through the head towards the case, but havent tried that.

Once all the tubes are out, clean them up, install the new seals, and oil them and reinstall.
If you have to reinstall them the convoluted way, then you will have to put the clean tube back in the head and put the new seal on from the head side.

The old-schoolers say oil only on these seals and dont nick them going back in the holes (some hole edges are sharp).
I used a non-hardening loctite product similar to teflon paste.
IMO Please try to avoid the RTV silicone method, but some do it that way.

If you had to wait to remove the pushrods until the tubes came out, remember to put those rads back in as you reinstall the tubes.

Then reinstall all the pushrods, and reinstall the rocker arms.
BE CAREFUL as you WILL get some of the pushrods stuck in the engine side not seated into the cup on the lifters.
You will also "pinch" a pushrod or two as you try to tighten them down on the rock side.

I try to spin the engine a time or two as you get the rockers torqued down to make sure everything is moving.
Then make sure the rocker bases bottom out on the head and torque the rockers down.

Reset the valves using your preferred method.

And since you absolutely must reset the valve lash, at the onset, simply loosen all of the lifter stop-nuts fully to relax the rockers on the push rods on all four / then upon reassembly, you will not have the pinch issue / which may alter your torque values.

If you have trouble getting the pushrod tubes out like I did, don't waste your time trying not to damage them. New ones are cheap and can be had at vw shops.

Thanks for the help.

I've gotten one side done... I used the motor oil on the seals.

Thanks again.