System Rescue Fedora 14 / Additional SW on Live System

Hello,

my Fedora 14 install is not booting anymore, from what I can tell it
hangs while trying to mount nfs shares.

system (Scientific Linux) on a flash drive. First and foremost I want
to know, how can I install additional packages on that live system
that I might need. Does it work like a normal system? I.e. I add the
repositories and yum install $package?
Next question: I don't necessarily want to kill the F14 install and
start from fresh, I am very much interested in why I am not able to
boot anymore and how to fix the problem. I tried to look for mtab from
the live system but didn't find anything.
In case this helps:

Observed system behaviour before the reboot failed:
Graphical user switching led to unusable shells, i.e. I couldnt't log
out from one user and log in to the previous one. I'd end up with a
text console and screwed up resolution. Also did this obscure console
not accept any standard shell commands, so something must have gone
seriously wrong. I also fiddled with gnome-keyring-manager by renaming
it in /usr/bin/ and by adding killall gnome-keyring-manager to
'Preferences - Startup Applications - New'. This was unrelated to the
log out issues bc I only did it after a first (successful) reboot.

Any help greatly appreciated.
Urs

Any ideas as to how I should proceed?

Next question: I don't necessarily want to kill the F14 install and
start from fresh, I am very much interested in why I am not able to
boot anymore and how to fix the problem. I tried to look for mtab from
the live system but didn't find anything.