Bob Brookmeyer: ''Through a Looking Glass.'' Brookmeyer, trombone; Mel Lewis, drums and percussion; Jim McNeely, piano; Marc Johnson, bass; Dick Oatts, soprano saxophone, Tom Harrell, trumpet. Finesse FW 37488 - Bob Brookmeyer presents Bob Brookmeyer in this set of original tunes and overdubbing of his trombone. It's an adventurous, exploratory set, something new from Brookmeyer, former exponent of the West Coast school of jazz in the 1950s, and a longtime associate of baritone saxophonist Gerry Mulligan. The overdubbing comes off with considerable success - all the tracks are spontaneous improvisation, with Brookmeyer ''responding freely to the material at the moment,'' as he points out in the liner notes. He has surrounded himself with players who support and contribute to his creative efforts - Dick Oatts plays the soprano with fire and conviction, and trumpeter Tom Harrell is surely one of the brightest new voices around, worthy of a lot more recognition. Pianist Jim McNeely's two-handed approach to lines is refreshing, and the remarkably sensitive bassist Marc Johnson (Bill Evans's last bass player) does some fine contrapuntal work with Brookmeyer's trombone. There's lots of variety in the compositions, from the pretty bossa ''Daisy'' to the fierce and thunderous ''The Magic Shop'' to the up-tempo Latin groove and avant-garde romp on ''Top of the World.'' The rhythm section, which includes brushmaster Mel Lewis, is free and floating, but still swinging.