2008 Toyota Corolla damage to steering system when coasting

I have recently bought a brand new 2008 Toyota Corolla, 5 speed manual, which is said to get 53 mpg (Canadian, or Imperial) on the Highway, and 40 mpg in the City.

So far, using very few active hypermiling-style techniques (my wife doesn't like it when I coast with the engine off ;o), I am averaging 42 mpg combined, a little lower than I might have expected, though I am not surprised, as there seems to be a general consensus out there that manufacturers' stated fuel efficiency ratings are notoriously overstated when compared to real-world driving experiences.

However, my real question is about the negative effect (if any) on my car's power steering system when I steer with the motor off. As you know, with the motor off, the (presumably hydraulic) power steering doesn't work, but you can still (with some effort) turn the wheel to steer the car. When coasting on fairly straight stretches, this doesn't seem to be a problem, because only small changes in steering are needed, but I notice that if (say) I come to a street corner and want to turn the corner while still in "coast" mode, it takes a lot of effort to turn the wheel that much -- I experience great resistance from the steering wheel.

So, my question is, does anyone know for sure if turning the wheel on a power steering vehicle -- when the engine is off and the hydraulic system is not working -- does this harm the car's steering system? For example, does it put too much pressure on the hydraulic hoses, or on other parts of the steering system? I suspect if I just asked a Toyota mechanic he (or of course she) would probably say "Don't do it", but I really want to know if there really is any danger of harming the steering mechanism by steering the car when the engine is off.