Speedread? in photofocus?
Purpose, affirmation and close for each page? Could work, when you entered the appropriate state with each 'focus'.
Frankly if the speaker is getting a little boring I'd just start flip flip flipping the pages (staying in photofocus after having stated my purpose etc) and maybe speaker would liven up the talk a little seeing this. 
If it's effective? I'd say it would probably depend on how effective you find your activations in general and compare for yourself. Perhaps a better time to preview and pull out trigger words than actually attempt to photoread. Great practice for seeing the blip page though. Seeing it only takes about 4-6 minutes to photoread the average book if activation seems elusive then just photoread it again.
See what works for you. Remember if you have doubts (which by your post suggests you do) then your doubts will probably reduce the effectiveness. As for instructor speaking hurting the effectiveness, photoreaders can photoread anywhere with experience.
Alex
