I have a .reg file I use to modify Disk Cleanup behavior, add items to the Regedit favorites list, and other tweaks not covered in nLite. Is there a way to integrate .reg files into the installation? If not, could we get one in some future version?

Thanks.

Simply import it into Run on first boot?
Inside your last session.ini file aka preset file i have
[GuiRunOnce]
TimeOut /T 40
CMD /R %Source%XP.bat
rem should not see me
Pause

Where the XP.batch file does f.ex silent install of .net framework and similar things. Just have it load from such a place, and you will be fine i guess.