Very uncomfortable motorcycle boot lining

[Simon.Pieman]

Have you considered stuffing the boots while your not wearing them? Something like a tin of beans would work just to help wear in the leather and widen out the heel?  There's always the old bucket of water trick too but not sure if that would work on motorbike boots?

You can also stretch boots by pushing a plastic bag into each boot and filling it with water, then you tie a knot on each bag and put the lot into the freezer. The water expands and stretches the boot.
Only do it once or twice, if you go mad it will certainly damage the boot.
For a liner I would glue in a pair of those green goretex army surplus socks you can get on eBay.