Okay thanks for the info, I will give it a try using your method.

That part number you reference is the window rubber for a left door of a wind-up window Mini.  I recently replaced both driver and passenger door rubbers on my '73 since I had the doors torn completely apart.  It's difficult to explain how to install in words but I'll give it a try.  Obviously you have to have the glass and regulator out to install these seals.  Ok maybe not obviously but I doubt you'll be able to install the rubbers with the glass in the door.  There is a short section of the rubber seal that is narrower than the rest.  There is a corresponding section of the track in the door that fits that profile (IIRC it's at the rear of the door and is narrower to clear the door latch mechanism).

I started there by pressing the rubber into that slot and worked the rubber into the slot on the entire rear of the door.  Next I started at the front where I pressed the rubber into the channel.  The remaining task was to fit the rest of the rubber into the track in the top of the door.

It was a finicky job but pretty easy once I figured out the orientation of the seal.  I had massive problems getting the windows to wind up once the new rubbers were installed.  Months later I sprayed some teflon silicone lubricant into the rubber seals where the window seats when closed.  Now the windows wind up very easily.

I bought window channel (pam3077) and I am wondering how exactly it goes into the door. I have the Mini manual, but it shows the sliding windows.