Just saw your post and wanted to say that it is not that difficult to replace the halo weatherstrip. I recently replaced both sides of my targa top and the halo.
The link provided earlier looks to be a good one although I didn't read it from top to bottom.
I can provide a couple of tips that may/may not be in that link:
1-do not remove the tape covering the glue until you are sure about the position of the weatherstrip.
2-get as much of the old glue/gunk off as possible even if you have to scrape down to the metal. Just be careful not to scrape anywahere that will be showing after the halo is installed.
3-take pictures of the existing halo installed on the car for reference.
4-take note of how the existing halo looks as you remove it so you can kind of see how you need to put it back.
5-I stood (in socks) on my two seats and worked with the new weatherstrip from the center out. There a couple of screws on each side that you need to make sure line up before removing the tape over the glue.
If you have any questions while you are doing it feel free to call me at 443-956-4927.