Make sure you know exactly where you want your computer setup to be and have some idea where you want him to run the cable to get to it. Bear in mind that he will probably be very reluctant to do anything under floorboards or in your loft space and if you live in a terrace it may prove difficult to place the wall socket in a room at the back of the house (assuming it's the street out front that's cabled).
And never forget the true wisdom when having any kind of installer or technician vising your house - keep him well oiled with tea and cherry bakewells, it makes him far more likely to go the extra mile for you.
