Plant-inspired inflatable eversion robots with their tip growing behaviour have recently emerged. Because they extend from the tip, eversion robots are particularly suitable for applications that require reaching into remote places through narrow openings. Besides, they can vary their structural stiffness. Despite these essential properties which make the eversion robot a promising candidate for applications involving cluttered environments and tight spaces, controlling their motion especially laterally has not been investigated in depth. In this paper, we present a new approach based on model-based kinematics to control the eversion robot's tip position and orientation. Our control approach is based on Euler-Bernoulli beam theory which takes into account the effect of the internal inflation pressure to model each robot bending segment for various conditions of structural stiffness. We determined the parameters of our bending model by performing a least-square technique based on the pressure-bending data acquired from an experimental study. The model is then used to develop a pose controller for the tip of our eversion robot. Experimental results show that the proposed control strategy is capable of guiding the tip of the eversion robot to reach a desired position and orientation whilst varying its structural stiffness.