This is basically a point and click admin tool. I have tested this on TF2 but I am releasing under CS:S>Server Administration, as it should work on CS:S just the same.
I assume you know how to install a script. When installed, and on the game just hit mouse3 to activate the script (this must be done each time you play your game). Use the mousewheel to change the power done, then aim hit your mouse3 button (click the mousewheel) and voila!
This script requires SourceMod. It makes use of your mousewheel, so only install if you don't use it!
// SourceMod AdminGun by Bojero
alias admincmd bindbeacon
bind mouse3 "sm_chat SM: ACTIVATED; bindbeacon; bind mouse3 admincmd"
alias bindbeacon "bind MWHEELUP bindkick; sm_chat [ SM: BEACON ]; alias admincmd sm_beacon @aim; bind MWHEELDOWN bindburn"
alias bindburn "bind MWHEELUP bindbeacon; sm_chat [ SM: BURN ]; alias admincmd sm_burn @aim; bind MWHEELDOWN bindslay"
alias bindslay "bind MWHEELUP bindburn; sm_chat [ SM: SLAY ]; alias admincmd sm_slay @aim; bind MWHEELDOWN bindkick"
alias bindkick "bind MWHEELUP bindslay; sm_chat [ SM: KICK ]; alias admincmd sm_kick @aim; bind MWHEELDOWN bindbeacon"