I'm not going to repeat this scene word for word as I'm assuming you've seen it already and that you don't need a repeat, I'm just going to make a few points that are different before moving on. Also, I'm scared I might butcher what is meant to be a heart wrenching moment, so I'm just going to keep it simple.
Prologue
"Minato, I'm so sorry, I can't control my actions."
"It's all right; I noticed something was off when I saw your eyes mimic the Sharingan." Minato spoke as he did a series of hand seals, summoning an altar. He then placed Naruto on the altar.
"Now Naruto, I wish it didn't have to be this way, but I'm going to be placing a very heavy burden on your shoulders. Now grow to be a strong shinobi someday, all right?" And with that, Minato did another series of hand seals, causing the Shinigami to rise from his back, holding Minato's soul in his hair. Suddenly, it shot its left hand through Minato's chest, and then towards the Kyuubi, which grabbed the Kyuubi's soul and started to pull towards Minato. "No, seal it all within my son." The demon showed no sign of hearing this order, but it started to pull it into Naruto.
"Minato, are you sure he can handle the entire Kyuubi without weakening it first? And besides, why are you using the Reaper Death seal for this? Kushina asked in shock and sadness.
"I'm sure the Kyuubi is purposefully trying to weaken itself, so I'm sure he can handle it; and the Reaper Death seal is the only sealing jutsu that is strong enough to seal a Bijuu without first putting it within some sort of holding state. I wish it didn't have to be this way, but I'm counting on you to take good care of him." Kushina started to cry, but she understood.
"MINATO!" the Kyuubi shouted, as it started to thrust one of its clawed hands towards the altar with Naruto. Minato and Kushina bot leapt in front of the massive claw headed for Naruto. It pierced both of them, but they stopped it just before it reached Naruto. "SEAL ME MINATO, I CAN'T FIGHT THIS CURSED INFLUENCE FOR MUCH LONGER!" the Kyuubi roared. Minato then summoned a rather odd looking toad.
"Gerotora. I'm going write the sealing key, when I'm done, I need you to go to Jiraiya." After having the seal inscribed the seal within the scroll toad, it disappeared in a puff of smoke. " Now then; EIGHT SIGNED SEAL!"
