afni.nimh.nih.gov

This question comes up occasionally, Unfortunately, we don't have a way really inside AFNI to do this other than simple unix tools to replace slice data in existing DICOM files (e.g. dd and redirection and appending (>,>>)). There is an old thread with suggestions for various software packages that might work here:

http://afni.nimh.nih.gov/afni/community/board/read.php?1,47494,47503#msg-47503