At this moment I am trying to install Slackware to my Sony VAIO
VPCEJ-28FX laptop. Booting from USB, at the "boot:" prompt, my
keyboard doesn't respond; not even to ctr+alt+del.

The only thing on the machine is a partition of Crunchbang, which I
will likely install over for now, then include in its own LVM
partition later down the line.

Lookups online haven't been of much use for this particular issue,
as most items or suggestions refer to altering kernel params or
other such things which haven't yet taken place on my machine as of
yet (from install perspective).

Thanks for your correspondence.

No matter how many times I attempted USB boot, same symptom. Went back and created DVD instead, no issues. Case closed.

My Vaio VPCEB24FX dose the same thing. last time i beilive i tried Slackware from USB it was around the time of 13.37. I used a derivative of it on my Vaio and no mouse, no keyboard. this is from USB. the Slackware 13.37 DVD did however work. This was one of the few times when my Vaio didnt comply, usualy mine neverv gives me any problems.