Your best bet for getting him to spawn is to do the Hyperius 4-player trick.
Touch Hyperius' gate, and the game will think you're in 4-player mode. Go to an area with varkids, and Verm will spawn much more quickly. --- Currently playing: Borderlands 2, The Cave, Paper Mario: Sticker Star
I know the trick, I know how he spawns, I just need a road dog to ride with me so I can stop killing half my chances for second. Winds.
In the 4 man trick ffyl time is increased to 4 player mode and damage dealt to enemies, sans raid bosses besides verm, does not recover. You can die as much as you want but eventually you will kill him. --- They're not going to say no because of the implication.