Installing latest Debian

[Christian]

Hello all,
have just joined this list. I have looked in the Speakup archives and found that it is possible to install Debian with Speakup, but I want to use BRLTTY. From what I understand BRLTTY is included on the CD but I have tried typing at the boot prompt:
install brltty=ts,ttyS0 but with no luck. If this doesn't work i'll need to use Speakup.
Any ideas?
Many thanks,
Christian