Kay Thompson and CBS-TV's "Playhouse 90" got together for a Thanksgiving offering in the form of a teladaption of her "Eloise," and while it wasn't exactly a turkey, it wasn't pheasant under glass either. Leonard Spigelgass turned the book by Miss Thompson and Hilary Knight into a script of sorts; Miss Thompson added five nondescript songs and producer Martin Manulis and director John Frankenheimer delivered the show's only real wallop in the person of Evelyn Rudie as Eloise herself.

The show's real delights came when six-year old Miss Rudie was on camera. For one thing, she's a dead ringer for Knight's pictorial creation. For another, she's quite a little actress -- she created a characterization of they part that was perfectly in keeping with the book and a delight in itself. Moreover, her scenes were the only ones that really came alive, particularly the one in which she puts Bartlett Robinson, her lawyer, through a medical examination while he's reporting her latest stock splits, and the one in which she twits Jack Mullaney, her tutor, by repeating everything he says.

But except for Miss Rudie's occasional scenes, the show was on the flat side. Of course, attempting to create a story from the book was a near impossibility to begin with, and Spigelgass used as his premise a threatened divorce by Eloise's parents, with a romance between the tutor and the chambermaid as the subplot. But he also crowded the plot with celebrities -- Miss Thompson, Ethel Barrymore, Louis Jourdan, Monty Woolley, Maxie Rosenbloom, Charlie Ruggles even Conrad Hilton. And with the plot sidestepping the celebs, things just never got moving.

The unwieldy cast included Mildred Natwick in a superb piece of nonsense as Nanny, the governess; Hans Conreid as an openhearted waiter; Inger Stevens as the pert chambermaid; William Roderick as the Plaza's manager and the above-mentioned Messers. Mullaney and Robinson. All in all, the supporting cast did better than the celebrities. As for Miss Thompson's score, the "How to Raise a Child" patter-chorus number had movement and good lyrics, but the rest was undistinguished. The Lennie Hayton orchestra backed the show nicely. Art director William Tyler Lee's sets simulated the Plaza nicely, and the one of Eloise's room was a honey. But director Frankenheimer, while milking the performance of Miss Rudie, had too many characters and too little script to contend with.