I assume you know what an injector pump looks like, pic is one that is not yet mounted. Now if you look at it, on the oposite end of where the steel lines are connected you will see there are three (3) nuts threaded on three (3) studs, one nut on top, one nut on each side close to the bottom, each nut requires a 9/16" openend wrench to loosen them, there are special C shaped thin box wrenches for the bottom two (2) nuts. pic shows wrench on top of box. Now after marking (center punch) the mounting flange, as icanfixall said above, loosen all three (3) nuts, move (twist) the IP body to your left (or passenger side of the vehicle), about the thickness of a Dime ( a Dime is a US coin), then tighten all three (3) nuts. By doing all of that you have in effect advanced the engine timing about three (3) degrees, moving the IP towards the drivers side will retard the timing. With out a timing device, you cannot tell exactly what the timing is set at. It should be at 8.5 to 9 degrees (before number one cylinder piston is at top dead center--ie:BTDC).
In the first place, what makes you think you have to advance or retard the timing?