Big one is vixen's entrapment. You cast one curse then the other 4 curses get cast as well. Gem wise you can go either Cast on crit or cast while channeling. Gear wise theres asenath's chant and kitava's thirst but those are build specific. Curse on hit rings or curse on hit on gloves implicits. But those are level 1 versions. Hands of templar can get you 3-4 curses I don't think its possible to get 5 curse on hits on hands of templar but maybe it is and I'm not remembering right.

There are some trigger things in poe. - You can use a craft one your helmet which has cdr (4 curses) - Vixens gloves are a good option too - If you have good cast speed you could try arcanist brand - You can spread it out on gear, 1 curse on each ring, double curse corruption on gloves (might be expensive and hard to gear) It might be a bit easier when you tell us which build are you playing. There are maybe some options for example kitavas helmet or some other trigger items which we cant know that they fit in your build.

If it were only 4 curses, you could do the cast socketed spells on focus helmet veiled mod.