For premade models simply transfer the hlmt over to the desired map
For injected models link them to a hlmt and transfer it over into desired map.
-Step two Relink your models
Do this by Swaping hlmt out over a bloc perferably one that is not spawned on map, However It is a very wise idea to start off by making the hlmt spawn over a bloc that currently spawns in the game for reason of seeing if the game freezes or to see if your model shows up ingame. If all is green and everything is set up the way you imaged it would be then unlink the model ingame and swap the hlmt back to its original hlmt. Then swap hlmt over a bloc that is NOT spawned in game.
Keep in mind if your doing a whole model with perfect jpt. Seperate the model and distribute it out through the blocs. for example left arm of new model needs to be seperated from the body and placed over any bloc to later be markered over masterchiefs left hand.

-Step three Copying the broken map
At the time of writing this tut entity has a broken ident problem that I will address on how to bypassing it. 4/5 your going to break your map like this so copy your desired map, paste it and rename "copy of ______" to "_____-broken-map". Now open broken map.

- Step four chunking required variations (assuming you are using entity from here on out)
Go to hlmt>warthog/warthog go into entitys chunk editor click on variation then default and copy default to clipboard, then goto masterchief [(mp) If multiplayer] hlmt go to his variation then default and overwrite selected chunk and then click add meta to map. Now open up chunk adder again under masterchief [(mp) if multiplayer] and click on variation>default>unknown>chaingun.vehi and duplicate it to how many parts of the model you will be having. Masterchief has 15 markers or model pieces. (to see what they are go to masterchiefs model then tag editor then look at his marker boxes). Determine which points you would like to link your model pieces to and how many you need. example being your models left hand to masterchiefs left hand would be one chunk. How many you need is how many you will clone minus the one you already have. So in the clone box put # chunks and click clone then add meta to map. You should get broken idents. Thats fine.

Step 5 transferring working tag to working map
Open up chunk adder under your bipd once more.and open up variation and copy default to cllipboard. Now open up your non-broken map and and go to the same bipd's hlmt chunk adder and overwrite its default and then add meta to map. This time their should be no broken idents.
You may now close out your broken map or delete it for that matter.
Step 6 linking your model
Goto masterchief hlmt in meta ediotr and show unknowns. Then scroll down till you vehi -warthog chaingun. Change that to one of your blocs your model/hlmt is on (I used hubcap). and do that for the rest of the chunks you added via dropdown box. Then its time to link your model to the bipd.
Change the top SID to the name of one of masterchiefs markers. If you still haven't checked save your progress goto model tag and look through the markers and write them down. Then head back over to hlmt of the chief and in the top SID above the bloc you added change the sid to masterchiefs marker via typing it in then click the drop down box, then clicking the one you typed in and save. do this with the rest of your models.

Step 7 linking the marker
Goto masterchiefs model and open up the tag editor. scroll down to the marker. see those coordinants? Yes thats right this is where you are on your own. have fun guessing and checking. I recommend minusing or adding by .2. on each coordinant to see change. Good luck.

Step 8
Null out masterchiefs lods in model by changing the values under LOD to -1.
Thats it! now hurry up and be the first one to inject a fully working model bipd into halo2!
For more help on limb positioning look to TURK645's custom jmad tutorial.
CREDITS
TURK645
SHADOW LAG
PS:
MC SP has:
body
drop
drop_left
drop_right
flashlight
head
left_foot
left_hand
right_foot
right_hand
shield_recharge
target_head
target_leg_l
target_leg_r
target_main
Refer to turk645's custom jmad tut for fixing raw pitch roll for moving your model along axis by numbers.