I don't know if you would be able to find the fixture for installing the upper/inner bushes anyways unless you took your parts to an old volvo mechanic who may have the fixture or already made something up. I tried it without the fixture and tried to make something out of wood and a vice but it completely failed due to my lack of consideration of the great forces involved (slightly bent my arms). Basically you need to make a very strong jig that will maintain the geometry of the upper arms while the bushes are installed onto the pin and into the arm. There are countless ways of doing this, if I did it again I would spend some time cutting and welding some steel together into the appropriate shape. Or maybe a volvo club has one you can borrow? If you spend the time making/procuring a good tool, the actual installation will be very easy and worry free.