Yes, Altiris puts in it's own ImageX command line options and other commands if someone chooses to use ImageX to capture or deploy.  As to where these details live, I've never found that out.  Up until Windows 7 everything just worked.  When W7 came along, I explored all kinds of files in my eXpress share looking for a way to modify these commands and was unable to find where it is generated from because I wanted to modify it.  However, given the fact that we haven't upgraded to 6.9, sp3, I had to basically make my own scripts for capturing and deploying images.  I don't have the capture string posted in this thread but the apply string is posted here: 

https://www-secure.symantec.com/connect/forums/alt...

Check out my last thread towards the bottom.  So far, things have been working great and we have been imaging away without any hitches.  I believe that WinPE can be locked out by itself to prevent "tampering" during the script executions.  I'm not in front of my DS console right now so I can't verify that.  I'm not sure what you mean by distribute image tag so I might wrong in my thinking of what you are asking for.  Anyway, I hope the other post helps.  One last thing, in my WAIK folder in my eXpress share I had to update bootsect because the old version didn't allow for the /mbr option.