Rick Mabry responded to me:

>>Tchaikowsy used 5/4 at least twice elsewhere: once in a ballet
>>score,
>
>Do you know which?  I let a few of the ballets play past me the other
>day and tried to stay on guard such, but might have missed it.

I will have to look it up from a tape, which I have stuck away somewhere.
I recall the commentator saying that Op 72 wasn't the first time he had
done it, as it occurred also in the ballet....; alas I forget.

>It's in Op. 72 (18 Morceaux for piano), no. 16, thanks for the tip.
>I looked for it and found it on a two-disk set of Tchaikovsky piano
>music (Michael Ponti) that looked worthwhile.

The tape I mentioned is a broadcast of Pletnev playing a selection of
Op.72 which is stunning!  I don't know whether it made it to cd.  Ponti's
technique is great, but I don't think he often manages the beauty of
that Pletnev gets.  On the other hand I haven't heard any recording of
the Moskowski concerto which even approaches the sheer effortless verve
of Ponti.  Other people want to make more of it than the thoroughly
enjoyable virtuoso piece it is.  I always feel more cheerful when I
listen to it; a critic compared it to a glass of champagne.

I will let you know if I find the tape: at a guess--I repeat a guess--
the 5/4/ waltz is in 'Sleeping Beauty'.

Cheers

Ernie