I'm not sure how capable Tahoe is, but you could have a go at this method:
Create your new collection tag and take note of its header. Then go look for the header of the original collection.
Now, there's no 'simple' way to go about this unfortunately, models are really poorly handled overall in the myth engine. Duplicate each of the other tags (cref, geom, mode) and rename them to something unique. Hopefully you'll name the collection along the same lines.
Once duplicated and renamed, you have to manually change the headers of each tag to something unique (related to the name of the file preferably). Once you've got all this done, you have to open up a Hex Editor, and open each of the 4 tags. I think the way it works is the Model starts the tree, it calls on the Geometry, which calls on the Collection Reference, which calls on the Collection. If you open each of the 4 tags in your hex editor you have to look at the first handful of bytes and find the headers associated with the original model in question, and change them to the subsequent ones you've created.
No quesiton, this is a bit complex.
The easier method, requiring a mac, would be to use Vegas. You would export the original model's textures, create your own new textures, index the whole stack of them together into 1 colourtable and then reimport the re-indexed originals into the original collection, then add all your bitmaps. In the sequences palette in amber/oak you can alter # of views, so you duplicaate all instances x2 and then add in your versions of the bitmaps. Once you've made your 'master collection' you can go into Vegas and just open up the original model in question, go to the Permutations tab, and 'add permutations', then with the new perms you toggle through to your new set of textures.
I've used both methods in the past successfully. Good luck. Models suck
