Jerome,
Your last post on this was in french so I was unable to follow what your experience was with using the "accept dd" command.
I used this method to install my SME server which had a SCSI CD-ROM and HDD connected to an ISA Adaptec 1510 SCSI controller with no problems.
I have used an Adaptec 1200A Mirroring Controller (based on a highpoint chipset, I forget which one) in ESSG 4.1.2 before but NOT during installation (as that server had a separate boot drive).
If you could repost (in English) what your experience was, it might be helpful for others who may be attempting the same thing.
Kelvin.