GreedyHMA might allow you to do it if you can bypass it's attempts to do a pulldown, there is a vertical filter in it. Not all that familiar with it's ins and outs.
TomsMoComp might be worth a try too. http://home.comcast.net/~trbarry/downloads
Although it's for doing a pulldown as well, set it to: TomsMoComp(-1,-1,1)
These settings should cause the vertical size to double (instead of doing a pulldown) and perform slight vertical filtering to remove remnant artifacts. Afterwards you'll need to resize it to cut the vertical resolution in half again.
Sharpening is up to you.
Anyway, if you want to google around, you are looking for a "Verical Filter". It's what is commonly used to remove interlace artifacts.
Edit: If you aren't familiar, undot() removes small single frame dots (spatial filtering). Deen() (among others out there) is a temporal filter commonly used to remove heavy film grain. They are frequently used together, though I find undot to cause more troubles than deen.