THE CONCEPT: Two multi-skilled dancer/choreographers -- Maurice Hines (see him with famous brother Gregory in "The Cotton Club") and Mercedes Ellington (a former June Taylor dancer and frequent Broadway performer) -- pool their talents and put together a temporary company. Called "Balletap U.S.A.," the troupe seems to aspire, on the evidence of its name, to merging the two dance forms, or at least expanding the language of tap.

The Catch: What Hines and Ellington and their lively young company have come up with for their two-week debut engagement at Ford's Theater (a low-cost, last-minute replacement for the scrubbed "Three Musketeers") is a slight and somewhat ragged evening that will need more than just time to jell into something more substantial.

The ballet connection is a tenuous one, with a few faint nods to classical dance -- clumsy lifts, a twirl here and there. The dancers, too, are substantial figures, not the frail, delicate beings of ballet, and the costumes, mostly of the too-shiny, too-revealing variety, emphasize their earthbound bodies.

Hines is a casual charmer, and his moments of movement are pure pleasure. In his "Tribute to Erroll Garner," Hines dances alone on a darkened stage, appealingly loose, as if he were rehearsing one last time before an audition. Ellington is less memorable, though she makes a splashy entrance as a cross between Jennifer Beals and the Bride of Frankenstein in a solo spot set to "Maniac," one of the "Flashdance" hits.

Perhaps Ellington's television training is to blame for the preponderance of variety show- type dance -- the "Solid Gold" syndrome. Much of the program is devoted to interpreting tinnily reproduced pop songs by Michaels Jackson, Sembello and MacDonald. Sadly misused "guest artist" Carmen de Lavallade, who has a splendid back, keeps it to the audience for most of the four minutes of her sandal- shod, Isadora-esque caper to a Roberta Flack ballad.

In the closing set-piece "Pretty and the Wolf," set to saucy Duke Ellington tunes, Hines and Ellington have a delightful, personality-filled duet, and the company shines in an exuberant swing session.

But it's a brief moment, and no matter how many variations on a theme, tapping becomes tiresome when it's the only thing on tap. BALLETAP U.S.A. -- At Ford's Theater through January 20.