You can't really because the people you want to hire for a few hours are all fully employed elsewhere. If it were possible to do this why would any company have

You can't really because the people you want to hire for a few hours are all fully employed elsewhere. If it were possible to do this why would any company have employees - management could just hire a rolling series of experts to build and fix all the technical problems that arose. The good news is the internet make working out the problems yourself possible, even if somewhat time consuming.