Ok, this is the update to the PMI tutorial. 5 less steps, a little more easy to follow, and it is all there this time. Nothing missing, I swear!
Ok everyone! In this tutorial, you will learn very simplified PMI, short for Perfect Model Injection.
1. First, open up the map that you want to get a model from to insert into another map. We'll use the Pelican from a30.map, or Halo, as an example in this tutorial.
2. Find the model that you want to import into another map, and click on it to highlight it. Next, check the box labeled "Recursive" next to the "Save meta" button.
3. Now, click the Save meta button. Create a new folder: C:\PelicaninBG. Within that, create a new subfolder, and then save the meta to C:\PelicaninBG\PelicanMeta.
4. Next, if you're extracting a machine for injection, like a door, or a vehicle, like the Pelican, you'll need to save the meta for the main tag too (like the tag for the mach of a door, or the vehi tag of the Pelican. Save it to C:\PelicaninBG\PelicanMeta again.
5. Now, with the map that you got the model and stuff from just now (a30 for this example), go to Tools > Generate Raw Model Offset List (CSV File).
6. Save the CSV file to C:\PelicaninBG\a30CSV
7. Now, go to Tools > Extract > Raw Model.
8. Click load CSV file, and navigate to, select, and open the CSV file that was just saved in C:\PelicaninBG\a30CSV.
9. Find your model in the list, or in this case, "Vehicles\Pelican\Pelican." Click it to highlight it, and hit extract. Save the model to the spot where the mod2 data that we recursively saved earlier is located in. In this case, it's in C:\PelicaninBG\Pelicanmeta\Vehicles\Pelican.
10. Now, close that map file. In HMT 3.5, open up the map file that you want to inject the model into (We'll use Bloodgulch here, if you haven't figured that out yet.
)11. With Bloodgulch open, go to Tools > Extract > Batch Extract, and extract the metadata to C:\PelicaninBG\BGBatch. Click YES to extracting the BSP. THIS IS CRUCIAL!
12. After it's done extracting, go to Tools > Extract > BSP/Model Sections, and extract those to C:\PelicaninBG\BSPVerticesIndices.
13. Then, go to Tools > Model Decrapper/BSP Builder. In the big empty box, right click, click add, and navigate to the folder where the model we're injecting is saved (In this case, it's C:\PelicaninBG\PelicanMeta\Vehicles\Pelican\), and select your model. If you get an error message, go back and do step 7 and 8 over again, n00b.
14. For Existing Vertex area, navigate to C:\PelicaninBG\BSPVerticesIndices, and select the .vertices file there.
15. For Existing Index area, go to the same folder as in step 15, but choose the .indices file there.
16. Do the same as in 14 & 15 with the .sbsp file in there. After everything is filled in, hit De-crap these models and build a new BSP chunk while we're at it.
17. Next, in C:\PelicaninBG, create a new subfolder, and name it "New Build."
18. Copy every last file from the C:\PelicaninBG\PelicanMeta folder into this new folder.
19. Then, copy every last file from the BGBatch folder into this folder.
20. Now, go to C:\PelicaninBG\BSPVerticesIndices, and copy the Bloodgulch.sbsp.meta file (NOT Bloodgulch.sbsp, but Bloodgulch.sbsp.META).
21. Navigate to C:\PelicaninBG\New Build\Levels\Test\Blood Gulch\, and paste that file there. Click "Yes" to confirm the replacement of the old file.
22. Now, go get a copy of the map that you're injecting the model into (The map file that you batch extracted earlier), and copy it. Paste it in the New build folder.
23. Rebuild the map file.
24. For original map file, choose the map you just pasted in the New Build folder. For additional files, select the model that you're injecting, and if you're injecting something like a vehicle, it's main tag too, like it's .vehi tag, or it's .mach tag (In this case the Pelicans .vehi tag.). Just those are needed. Everything else is added automatically.
25. Hit build, and then when it asks if any new vertices had been added to the original BSP chuck, say yes, and select bloodgulch.vertices.new in the C:\PelicaninBG\BSPVerticesIndices folder.
26. When it asks about the same thing for the indices, choose the bloodgulch.indices.new file in that same folder.
27. When it asks if it should update the starting offset, click YES!
28. After it's done rebuilding, copy the file to your Halo maps directory.
29. Delete Bloodgulch(.map) (ONLY IF YOU HAVE A BACKUP.).
30. Rename Bloodgulch.map.rebuild to Bloodgulch.map (Or just Bloodgulch)
And there ya have it! Perfect model injection in 30 easy steps! Any questions can NOT be sent to me over AIM (To STOPIMINGME), or by PM at Halomods.com. I WILL NOT ANSWER.
~Pkmnrulz240, Dark Cloud
Hope this helps you guys out!
BTW, any questions can be posted here as well. 
So, I made this, and I posted it here, as like I said, I saw some other people who were having a few difficulties with seperating PMI and SP>MP Conversions.