So, you want to use all your sprites from the older version of Half-Life
with Steam, no problem.
This tutorial is going to assume you know how to search your hard
drive and copy files to folders as well.
First you have to find the folder that you will be saving the
sprites in. For every user this folder is different since all
of your game information is stored in a folder with your e-mail
address you used when you registered for steam. The image below
shows an e-mail address highlighted in yellow. Replace that with
your e-mail address that is registered with Steam. Then continue
to the valve folder and you can copy your sprites folder there.
Some people may experience trouble with the missing file crosshair.spr.
Just make a duplicate of crosshairs.spr and name it crosshair.spr.
Once you do that, all of your custom sprites will work in steam.
If you make a models folder in valve, you can put your custom
models there also.
If you want to add custom models from your old setup, copy them
from your old half life folder and
create a folder called models and put them in there with the same
folder setup.