This can be achieved by chaining 3 transforms: T_center_of_rotation_translationT_rotationT_center_of_rotation_translation_inverse

However, this is not very user-friendly. There could be a fiducial point selector in the transforms module and if the user chose a fiducial point then that would be used as a center of rotation. The transforms module GUI could compute the resulting transform using 3 transforms as explained above.