In the 1950s, Jack Nicholson toiled at a series of supporting roles on TV anthology dramas and episodic series. Now, in the '90s, he returns to television on his own terms, as the center-stage honoree of this year's American Film Institute Life Achievement Award. The one-hour special based on it, taped a week ago and shown tonight on CBS, is the evening's very best bet.
* "Mad About You" (8-8:30 p.m., WMAR, Channel 2) -- On this new episode, Paul (Paul Reiser) and Jamie (Helen Hunt) find a secret cache of letters written by a previous occupant -- a similar starting point to that presented, a few years ago, on an episode of "thirtysomething," when Hope (Mel Harris) found some letters and became obsessed with them. "Mad About You," however, is Hopeless. NBC.
* "The Byrds of Paradise" (8-9 p.m., WJZ, Channel 13) -- How long will it take before this newest series from Steven Bochco Productions reaches out and connects with a former Bochco associate as a guest star? This long: In tonight's second episode of the series, a psychiatrist is portrayed by Bruce Weitz, who played Belker on "Hill Street Blues." There are some nice touches in this show, but, as in the premiere, problems are resolved too neatly and easily. Timothy Busfield stars. ABC.
* "The AFI Salute to Jack Nicholson" (10-11 p.m., WBAL, Channel 11) -- Seldom has the decision by the networks to cut back this series of AFI specials to one hour seemed as cruel as it does this year -- the first year, it should be noted, reflecting the Life Achievement Award's newly "amended" criteria requiring that honorees be working actors or actresses with significant work still ahead. Clearly, that's one concession to television, so why not make room for more time, more speeches and more clips? Warren Beatty is host -- and you don't even have to wait to see this show to begin enjoying it. Try predicting which clips have to be shown, and see whether you're right. Will CBS show the chicken-salad sandwich scene from "Five Easy Pieces"? The "Heeere's Johnny" scene from "The Shining"? Which scene from "One Flew Over the Cuckoo's Nest" do you pull? Or from "Chinatown," and "Batman," and "Easy Rider," and . . . How can you not watch? CBS.
* "Denis Leary's Blatant Promotional Special" (10-10:30 p.m., MTV) -- For this MTV pre-empts "Beavis and Butt-Head"? But at least give Mr. Leary credit for honesty in titles, and take it from there.
* "Pirates" (11:30 p.m.-midnight, Discovery Channel) -- There's a rumor that the Discovery Channel stole the idea for this documentary, but I suspect that's just another of my space-filling dumb jokes.