Can you buy an attachment for a regular drill to use to install drywall or do you have to buy a separate drywall screw gun?

You can buy just a special dimpler bit for drywall for about $3. It has a crown around thye phillips and stops penetration at the correct depth. This one is a bit over the top at almost $19. Dimpler Phillips Drywall Screw Setter, #2 # D60498 by Bosch For much less this works fine. Irwin Phillips Drywall Screw Setter, #2 # 3510641C by Irwin Tools

Awesome, thanks!