Good trick with the heatshrink. I normally use the pliers to get the seal in.
I forgot to post some details on installing the valve stem seals. There are several good references here for doing this job but there were a few details I wasn't sure how I would approach. This isn't a thorough, step-by-step, guide but hopefully it will fill in a few gaps and maybe help you decide if you want, or need, to do the job on your car. Mostly, I know we gear-heads just like looking at photos of someone else's engine problems!
This photo shows a piece of electrical shrink tubing on the right valve stem. Just put a piece of this shrink tubing over a valve stem and go over it quickly with a torch to make it shrink to fit the valve stem. You can use this one piece for each valve. It helps protect the valve seal from damage as you slip it down over the notch for the valve keepers. The deep 10mm socket on the left is the tool folks recommend to seat the valve seal. You should be able to seat the seal by hand but some recommend a few gentle taps with a hammer to make sure it's seated. I'm a little skittish of the hammer since I don't have the experience to know how much force it would take to damage the seal. As far as I can tell, you should be good if you lean on the socket with a rag to protect your hand. You should feel one or two clicks and the seal should be fully seated.