A method for cementing a casing string in a borehole includes the steps of moveably coupling an outer sleeve on a casing segment; making up the casing segment with the outer sleeve into a casing string; running the casing string in a borehole; displacing a cement slurry into an annulus exterior to the casing string; and moving the outer sleeve relative to the casing string to agitate the cement slurry. A transfer device is used to rotate the outer sleeve against the cement slurry. Multiple outer sleeves may be received on the casing string at spaced intervals. In one embodiment, the transfer device may include a mechanical clutch through which the outer sleeves may be rotated. The mechanical clutch may be driven using an inner cementing string that provides a supply of cement slurry to the annulus.