A method is proposed to control the transverse motion and x-ray emission of electrons accelerated in a wakefield driven by a laser pulse with transverse chirp. The dispersion of the laser and the nonuniform refractive index of the plasma channel result in transverse laser oscillations, which leads to transverse oscillations of the wake. Electrons accelerated inside the wake also undergo oscillations generating a wiggler like motion. Both the oscillation period and amplitude can be controlled by tuning the laser spatial chirp and the plasma channel width. As a result, the far field spectral distribution of the x-ray emission can be flexibly manipulated.