Any level restricted map, or special time map will likely not allow you to teleport unless you meet the requirements for that map. I'm not saying its impossible, just unlikely.
As for using a return scroll to as a teleport scroll, you would have to change the assembly code in such a way that would make a return call the teleport scroll function. Which is very possible, with map restrictions still in place however.
That being said, the only practical use for that hack that I can see would be to teleport to enemy towns.
But please continue learning, as that is what makes more hacks

.
And remember nothing is impossible!