Actually, no, it doesn't - base-installer is acquired by the installer at run-time.
For hardy and intrepid, pass apt-setup/proposed=true to the installer on the kernel command line.
For dapper it's more effort. I suspect the easiest way is to make sure that you aren't preseeding the locale, and then when the locale prompt appears, switch to Alt-F2 and edit line 113 of /usr/lib/debian-installer/retriever/net-retriever to add "$codename-proposed" after "$codename-security", so that the line looks like this:
for codename_extra in "$codename" "$codename-updates" "$codename-security" "$codename-proposed"; do
Actually, no, it doesn't - base-installer is acquired by the installer at run-time.
For hardy and intrepid, pass apt-setup/ proposed= true to the installer on the kernel command line.
For dapper it's more effort. I suspect the easiest way is to make sure that you aren't preseeding the locale, and then when the locale prompt appears, switch to Alt-F2 and edit line 113 of /usr/lib/ debian- installer/ retriever/ net-retriever to add "$codename- proposed" after "$codename- security" , so that the line looks like this:
for codename_extra in "$codename" "$codename-updates" "$codename- security" "$codename- proposed" ; do