I guess without seeing it, its hard to give ideas.
But I would look at running a cord over the sidewalk in a place where there is a step. Maybe you can stuff the cord in a crack between the step and the sidewalk.
If its just a one day thing, you could get a cord cover to run over the sidewalk. Don't want to do something like this on a permanent basis do to trip hazards, or getting chewed up in a snow blower.
The LED Warehouse