This is pretty much a beginner's tut. Should work for both, but I have trial. Therefore this is using HMT, with Phenom's plug-ins.
Steps:
1:Open your map(bloodgulch).
2:Scroll down to weapons, and click the + sign to open it.
3:Scroll down to weapons/frag grenade/explosion.
4:Look under screen flash and then under priority. Duration is how long it lasts, probably in seconds. Type 10(what I put).
5:Leave maximum intensity as 0.7.
6:Change Color(R) to 2, (G) to 0, and (B) to 1.
7:Scroll down until it says a bunch of options, and force is one of them.
8:Set the stun times to whatever(I left them blank), they are probably 1 = 1 s. Set the force to 20. Set the range by pressing 9999999999999999 until it says error, click ok, and hit backspace once. Do the same for Minimum as Maximum.
9:Click save.
10:Go have fun! Some people find this great, others may quit in 10 seconds(sore loser, becuase I'm great).
One thing about this: the grenade explosion can't go through stuff, so it's smart to chuck it where it can hit him but not you.