Breakdown of the commands:
use weapon_frag- swap directly to the grenade
wait 450- wait for the draw animation to finish
+attack- fire the grenade
wait 15- wait before releasing to ensure grenade is thrown
-attack- release prompt
wait 50- ensure -attack is run and the grenade has been thrown
lastinv- switch to the last weapon
The default bind used here is
T, but of course you can change that to whatever you want.
I played with the
waitcommands to try and get them as low as I possibly could, so they should work as fast as possible.