How to prevent network autodetection in debian-install?

I'm trying to use the Debian install media rescue mode on a Sun Ultra 10 so that I can use the shell to investigate an old SCSI disk I have. It seems that the last version of Debian where a SPARC build was available with anything more than a netboot image was wheezy (7.x). I'm using a copy of the 7.11.0 DVD 1 ISO. When I boot from the disc and proceed through the rescue install prompts I get as far as Detecting Network Hardware and at 0% the system hangs. How can I disable network auto-probing? According to the manual for wheezy on SPARC , the netcfg/disable_autoconfig boot parameter is provided for this purpose. However booting with rescue netcfg/disable_autoconfig=true at the SILO prompt does not appear to affect anything -- the Detecting Network Hardware step is still eventually shown and the system hangs. A responder indicated that the boot parameter netcfg/disable_dhcp=true is documented in the F8 help on some install media (although not wheezy for SPARC -- it has no such help feature), however I also tried this boot parameter and had a similar result. In search of ideas, I took a look at the example preseed file for wheezy , and it notes that the boolean parameter netcfg/enable can be used to entirely disable network configuration; however booting rescue netcfg/enable=false also had no effect. Perhaps the parameters just aren't propagating from the SILO prompt to debian-installer. Is there an alternate way to do this?