How do you lock the primary mirror on a C 9.25

I was wondering if any one knows how to lock the primary mirror on a Celestron 9.25 SCT and if this is a must for CCD imaging. I sincerely appreciate all of your responses
ashton

Installing mirror lock knobs involves disassembling the whole scope. an example (on a c-11, but in practice would be the same on a 9.25) can be found at:
http://personalpages.bellsouth.net/r/r/rritter2/Celestron_C11_Mods/#Section_4

Is a locking primary a must for ccd imaging? No matter what Meade says, the answer is no. Granted it's always wise to take certain precautions (i.e. guiding off-axis(not with a guide scope), trying not to image across the meridian, etc.); but is a mirror lock necessary? It never was for me....