This could become an interesting project. Obviously I prefer following your second option 
I'm just not sure how to help best, i.e. how to figure out how to actually go that route and install OpenWRT that way.
Where in your process are you stuck? Would it help you if I try opening my TM01 and attaching a serial connection, as I understand from your other post? I've done this in the past with other devices so I assume it's not a big challenge here, too.
But what would be a next step then? And how would we proceed from there?