I'm beginning to allow Dot and Buster to stare each other down for an
hour or so a day:

http://mywebpages.comcast.net/Takayuki9z/P1000207a.jpg

What I'm doing with them is playing with the cat charmer with them,
moving the wand back and forth between Buster and Dot, allowing both
of them to bat the toy.  Dot will still growl at Buster even while
playing, and will swat at his head instead of the toy if he gets too
close. :)

As well as supervised play, I'll let them both have full access to the
rooms at the same time.  When I do this, I escort Dot closely.  I keep
my body between the cats and don't allow Buster to approach closer
than about five feet from Dot.

Today, I was allowing them both to roam freely for a couple of hours.
Dot was lying on the platform next to me, but seemed to decide that
she wanted a snack.  She jumped down and started inching towards the
hall.  She looked at Buster's room - if the screen is intact, she'll
dash past it at this point, but she saw that it was open.

She dashed past it anyway, and encountered Buster, standing about 15
feet away.  She stopped, growled, then dashed a course that took her
past him.  As Buster readied for a pursuit lunge, I ran after Dot.
Seeing me following Dot, Buster hesitated and aborted the chase.

I quickly found Dot on the kitchen counter, waiting for the pursuer's
next move.  Seeing that the pursuer was me and not Buster, she jumped
down and purred.  She started eating her food.  Buster peeked around
the corner, watching anxiously as Dot ate.  This was Dot's regular
dish, but Buster had never seen Dot eat here before - he thought it
was his own second dish!  Dot, seeing him out of the corner of her
eye, growled.  Buster wanted to approach, but I shooed him away.

Later, Dot was on the living room couch, readying for a nap.  Buster
was tired too.  He curled up with his head on the carpeted scratching
post, and started to close his eyes.  Dot stretched out her forepaws
and partially closed her eyes too.  Then, Buster stretched and roused
himself, deciding that he wasn't so tired after all, and he batted and
ran after a sparkly ball.  Dot's eyes went wide.  Buster's play
eventually ended up with him going for a bite to eat in his own room,
where I went up and shut the screen.

They're both napping now, Dot on the sofa, and Buster in his room,
separated again.  Buster is now dreaming of how wonderful it'll be
when his hoomin finally lets him have Dot as his own personal chase
toy.  Dot now is dreaming of a utopia where no cats but her exist, and
she has dozens of hoomin slaves tending to her and feeding her ham.