as I have told, my T1 actually boot every time in recovery mode, instead of doing the normal update...
so it is definitely possible.. so I'm wondering this: is the update mode a recovery mode + update?
if it is the case, it should be possible to achieve recovery mode just with a proper update which stops the process...
I started to watch the p1 init code... and I think it just switch between normal boot and sd rescue boot..
the info about the button pressed at boot may be in /sys/module/rawdatatable/parameters/mmc_dev_no
(see /linuxrc in p1)