The music is the first indication that "The Chisholms," a four-part ministeries that begins at 8 tonight on Channel 9, might amount to something.

Elmer Bernstein has arranged themes from Aaron Copland's "Appalachian Spring," "Billy the Kid" and "Rodeo for "The Chisholms," and-as always-Copland covers the trek West with majesty.

Fortunately, writer Evan Hunter did not get carried away with the majesty of his enterprise, a la "Centennial." Nor did he go the other way and get lost in hackneyed B-movie plots, a la "How the West Was Won."

Judging from most of the opening episode (the last part of tonight's show and future episodes were not available for preview), Hunter's script effectively embroiders the mythic motifs of the Western genre into the story of one Virginia family heading West in 1843.

Robert Preston and Rosemary Harris play Ma and Pa Chisholm. Preston's role is especially well written to display bothe the necessary gumption and the oddball eccentricities of the pioneers.

There are three sons and two daughters. Glynnis O'Cnnor makes an appealing appearance as the bride of No 1 Son. Gavin Troster plays the scion of rival clan. He's in love with Chisholm Daughter No. 1, played by Stacey Nelkin. Sons No. 2 and 3 have one of the better greased-pig scenes ever filmed.

The Chisholms" should not take these words of encouragement as a sign that we want to see 26 episodes of them in a regular series next fall. Recent Western miniseries which have gone the series route have been trivialized and demeaned; one which did not, "The Awakening Land," lingers in memory as the best of the lot. Even "The Chisholms" may falter over the course of four episodes.

But tonight's debut, directed by Mel Stuart, is not bad.