I have done this a few times..it is the same as the tach..you have to pry off the needle--making sure that you do not break or make larger the hole that the pintle goes into..it just pops back on--don't put it completely back together untill you check to see if it goes to 0 with the key on..for the tach..the speedo should bounce back to 0 by flipping the needle up towards the numbers..or stop at the stop pin if it has one..harder to take the dash cluster out than it is to replace the gauge back..
Rich
I stopped after removing the center lower dash pad cover which gives access to the bracket that holds the steering column in place.
I found other instructions that state that after I remove the 3 screws that secure the speedo I should be able to give it a tug and be able to reach behind it to remove the speedo cable.