Got something to work.
I got a Backup of Summoners Rift (Winter) and I was able to start it on the sandbox.
I created a LoL-Patch (0.0.0.227 modified) and modified some LoL-related Files.
I think I should be able to play on "Old Twisted Treeline", 'cause I got a Backup of this map, found on my old LoL-Version on my Laptop
I'll try it later