Of course you should follow the guide from IComp, take out the mainboard and put it on a table before placing the Indivision.
The mainboard of your A1200 must be placed on a stable, level surface. First, place the socket over the Lisa chip, but do not push yet! Double-check that all pins line up properly. If the socket should be tilted in any way, it might be destroyed by the pressure that must be applied. The socket is in place if the board is level on the Lisa chip, but cannot be rotated any more.
