A new transceiver architecture for overloaded MIMO interference channels is proposed to fix the rate saturation problem of purely linear beamforming in this case. The proposed scheme is based on a mixture of linear beamforming and multiuser detection. It is shown that non-trivial degrees of freedom can be achieved by the proposed mixed scheme properly dividing the interference signals for linear processing and multiuser detection, and the achievable degrees of freedom of the proposed scheme are obtained. Numerical results show that the proposed scheme outperforms linear beamforming in overloaded MIMO interference channels.