In the present paper, we extend the dynamic mean-field density functional method which describes microphase separation phenomena in polymer liquids, to account for viscoelastic effects. The effect of simple steady shear on polymer orientation and elongation is taken into account by adapting the polymer configurational distribution function. We propose a simplified model for polymer chains in a simple steady shear how and show numerically that this model correctly reproduces expected conformational changes. The conformational effect is only of importance for high viscosity liquids and/or high shear rates.