If they want specific materials used, it would seem they would also expect those materials to be applied to the models in a specific way. Without the UVs, there's no way for KS (or any other program really) to understand what that specific application is. That being, exactly "how and where" to apply the materials to the models. Without the UVs your choices are the other standard mapping modes in KS (Planar, Box, Spherical, etc...). Maybe one of those could get close but it's hard to say since we don't know what the models or the materials look like.