how do u replace the dash panel

I'm guessing you mean the dash top panel and not the complete dash asm....
Pull windshield mouldings
Pull windshield
Clean up all goo from the windshield and seam sealer ect
Drill out spot welds and remove top panel
Fit new panel drill holes for plug welds
Prep weld areas with weld thru primer
Weld, grind, prime with epoxy and seam seal

Here are a few pixs....

http://1stgencamaro.net/gallerytwo/v/67-Camaro-Convert/album18/?g2_page=1