Seriously, it gave him a pogo stick.

 

LOL, robot Santa gives Zoidberg a pogo stick IIRC.

EDIT: Never mind, I didn't notice Aekiel's post since it was on another page.

 

Addressing the question in the OP: the solution to how he crosses thresholds etc. is that he doesn't.

While the faerie Santa does exist in the Dresden books, I find it likely that parents still buy kids presents, rather than they magically appear. I would think that people would clue on to the existence of magic, if every year a load of presents appeared from nowhere.

 

Which would probably indicate that good ol' Klaus has lost much of his power in recent centuries.

 

This.

It's more likely that the fae Santa exists and is immensely powerful because of the millions of children that believe in him so fervently, but has nothing to do with the actual giving of gifts.

No way. Almost every child in the US believes in Santa, with the innocent fervency that only children can achieve. That alone would be enough to give a fae humongous power. It's unlikely that he's gotten weaker at all.

That said, we're probably never gonna see him in the books, and I doubt he'll even be mentioned again in any more depth.

 

Nah, he tried that.

Was a pretty bitchin' battle cry, though.