I'm not sure if you realize this or not, but the Berserk pack is already included in Generations Arena.  Any map with a Medkit spawn works as a Berserk power-up for every class except for Arena and Strogg.  (Arena gets the Medkit and Strogg gets Adrenaline which is somewhat similar in function.)  And just like in DOOM, the Berserk power-up lasts until you die.  In fact, if you should ever play with Phoenix, you should never, ever let him get that power-up, because you will die... a lot. 

Load up Q3DM13 (Lost World) as a Doom warrior.  Look for the medkit item above the jump pad near the grenade launcher.  In place of it you will find your friend the Berserker.  Like Doom, it will restore your health to 100% and multiply your strength tremendously, and give your vision a temporary red haze.  Unlike Doom, you can carry it around with you and use it when you need to heal yourself in a hurry.  Removing the ability for Doom Warriors to Quad is a disadvantage I'm not willing to confer.  That was a very early design decision that ALL players should be able to quad regardless of class or weapon.

In addition to Doom Warriors, Slipgaters and Earth Soldiers also have their own form of Berserker available, since they also have melee* weapons.  Slipgaters have a magic box that looks like a miniature mega health artifact that makes him swing his axe with tremendous force, and Earth Soldiers have a bottle of whiskey (think drunken rage) that would make Jack the Ripper green with envy.  Doom Warriors get the most benefit from the Berserker since his fist attack is normally very weak, and combined with their speed they're best equipped to deliver a knock-out punch.  And yes, I hold the record for most berserk kills against real players in a FFA.  I forget the exact number, but it's somewhere around 48 I think.  I know I've made 27 axe kills with the Slipgater on Q3DM11 and won a game in the process using the Berserker.  (I was under the name "Gimli" in that one.) 

*The Quake 3 Gauntlet is not counted as a melee weapon for the berserker.  The damage inflicted is from a combined mechanical sawblade and an electrical discharge, not from brute force.  The Gauntlet is more in line with the Doom Chainsaw and already deals significant enough damage to not warrant a powerup upgrade.