There is no place where the boys can't go although there is a room
(the CIR - Cat Introduction Room) where I keep the new one while the
other cats have the run of the house. But after the integration that
room is open to all. I've never had an untested cat in that room
before however so I am concerned about disease entering the house.

But the foyer, that tiny room between the front door and the rest of
the house, is where the cat is likely to end up first. He's already
sitting on the front steps, freaking out the boys. Normally I don't
let the boys into that room since I use it like an airlock but
sometimes they come in if I have no plans to open the front door.

I guess I'm concerned about the logistics. I can get a carrier into
the foyer and once PS (I think that will be his name) is in the foyer,
put him into the carrier. Then he can go to the CIR where I keep him
until I can get him to the vet.

Seems like a plan?

It gives you such a warm feeling when they allow that first stroke,
all  be it fleeting..
It marks the first mutual intimacy of a life long friendship.
Good Luck, & I hope you have many leg rubs to come,
Purrs and affection coming your way
S;o)

And don't let your cats eat from a dish that the stray eats from.

Sue