Well, this wouldn't be as good as the original, but if it had to, I think it should go like this:
At the beginning of Season 4, Faith awakens from her coma in a sweat after dreaming that she kissed Buffy. She quickly escapes from the hospital and contemplates the reason her dream seemed so real. Was it just her imagination playing tricks on her or was it her Slayer visions trying to tell her something? She later discovers the tape Mayor Wilkins had left for her. She re-watches the video and then examines the device he had also left her. But instead of using the device on Buffy, she ultimately decides to use it on Giles, so she can see what Buffy is like when she isn't around. Faith captures Giles and leaves clues which point to a group of local vampires to distract Buffy, though Buffy believes it is Faith after discovering she had escaped. Faith locks Giles in a cave outside Sunnydale, drugs him, and completes the body switch. She returns frequently to prevent the true Giles from escaping. Faith, now disguised as Giles, returns to the gang and informs Buffy that he had slayed the vampires who took him. Buffy and the rest of the gang believe him straight away and continue life as normal. However, Faith's Slayer strength and skills had also been switched to Giles' body, so she has to fight to hold back when training with Buffy, as sometimes she would feel the urge to kill her as it would be very easy to do it disguised as Giles, but knows this is not how her plan is to work. Faith relishes in Buffy's sadness over Angel's departure and her horrible incident with Parker, but after discovering Buffy's happiness with Riley Finn, she decides to tear them apart by using Giles' magic books. However, Faith is terrible at magic and instead of removing Buffy's love for Riley, she accidentally removes Buffy's soul. With Buffy evil, she kills Parker, Riley's best friend, Forrest and Maggie Walsh in the span of two episodes. Faith originally loved the idea, because this is the Buffy she had always wanted her to be, but after realizing how very evil she had become, she reveals to the sadenned Willow and Xander that she had switched bodies with Giles. They are extremely angry and Xander wants to kill her, but knows he can't hurt Giles' body. She says she will give Giles' back, but she needs Willow's help to return Buffy's soul and to switch her and Giles' bodies back. Xander finds the soulless Buffy and talks to her, but after he mentions Faith was trying to kill her, Buffy quickly leaves before he can finish. She attempts to tracks down Faith, unknown to the fact that Giles is in Faith's body. The true Giles escapes after the drugs wear off, but is still too weak to make it back to Sunnydale. However, the evil Buffy finds him as he tries to explain that he is not Faith. Before he can tell her, Buffy lunges a stake at Faith's heart. However, Willow had completed Faith and Giles body switch five minutes ago, but since Faith's body was drugged, she could not explain what had happened. After stabbing her, Buffy's soul is restored and she realizes what she has done. She is sadenned that she had killed three people, aswell as Faith. Buffy says that she now understands how Faith feeled after killing a human and tells Faith she is sorry for everything, as she starts to cry. Faith also begins to cry as she weakly replies, "Don't worry about it B. We're even now. 5X5", and then dies. Buffy kisses her, picks up her body and heads back to Sunnydale
Well yeah, it's actually cooler if I had more time to put everything in, but I didn't have the time, so yeah, holler back at what you think.