I had issues as well. We got two new models in and the driver that worked for both was named the same but different files, their file sizes were different. Problem with that is Altiris will overwrite one with the other because they are named the same. I ended up adding one and then copying the folder elsewhere and then adding the other and copying it elsewhere. Then I renamed the folders to match the model it was for. Renaming seems to be ok as both models now work in WinPE4. Then I put both folders back in the CUSTOM directory and recreated the boot environment.
I added through the console and by using Bootwiz manually. I can't remember which one worked or if one didn't. They did not appear in the window like you say.
The driver for both models was the Windows 8 driver called E1D63x64 for the i217-lm or i218-lm.