The hooks can be obtained from the dealer (approx. $10.00).
Pull out the instrument cluster (slowly, do not overstretch the speedo cable housing) reach behind it on one side and disconnect the speedo cable (it is screwed on). This allows you to pull it out more, disconnect all the electrical wires and the vacuum hose (if you have the economy gauge) and pull it out. Don't worry about the connectors they go on one way only and can't mix them up. Smart engineering.
Once it is out taking it apart is easy. The needles come off by carefully prying them upwards. Installation is reverse.
By the way where did you get the white gauges from, how much they cost and most importantly what is the quality like?