Good idea! I used two chopsticks as they are longer. Placed them near the corner and use one of the T10 screw's hole in the side of LCD panel to prop it up. Fit perfectly and very sturdy. This gave me plenty of space to work with the replacement.

The Swiffer idea worked great! I just brush it over the LCD and glass panel lightly, and all dust particles are gone quickly. The screen after boot up looked beautiful. Thanks!

Watched the video guide and read this guide thoroughly, including all the comments, before starting the repair. It took me an hour, going slowly but surely. In the end the iMac powered up again and worked beautifully. For this repair, as some suggested here, I skipped steps 6 through 9 and only disconnected the vertical sync cable. I used two chopsticks (they are longer then pen) to prop up the LCD, using the holes of those T10 screws. Worked great, gave me two free hands and plenty of space to remove the power supply board (T10 screws, disconnect the two connectors), and put the new one in. Reconnect the V-sync cable, then remove the two chopsticks propping up the LCD and carefully lower the LCD back to its place. That's it. I figured the fewer connector touched, the better and it was a lot less stress. The magnet for the glass panel is very powerful. A couple of T10 when I tried to remove it got sucked over, but a small tweezer helped. BTW, be sure to clean any dust of the LCD. Thank you guys for the guide!