I've got a D-Link DWL-650 wireless card working perfectly in my new laptop, but there's something I can't quite figure out. How exactly do I specify a WEP key?

In /etc/pcmcia/wireless.opts, it seems that the KEY= setting is what I should be interested in, but I'm not sure exactly what the format of this setting is. If my WEP key were 0123456789abcdeffedcba9876 (hex) or "WePkeY" (password), how would I set those?

Actually, it depends on the driver. I've seen three different formats ...
01:23:45:67:89:ab:cd:ef: ...
0123456789-abcdeffedc-...
and
s:WePkeY
(which may have to be entered as 57:65:50:6b:65:59).

And, depending on the driver, it may not look in /etc/pcmcia/wireless.opts!

FWIW, the D-Link DWL-650 has changed chipsets without changing model number, so I can't really guess which driver you are using unless you tell the entire identifier (and maybe the relevant output from /var/log/messages).

-bbeers

I am using the orinoco_cs driver.

IIRC, orinoco_cs uses iwconfig to set the wireless params,
manually you can type commands like:

iwconfig eth0 key 0123-4567-89ab-cdef-fedc-ba98-76
or
iwconfig eth0 key s:WePkeY

the relevant section from man iwconfig is:

key/enc[ryption]
Used to manipulate encryption or scrambling keys and encryption mode.
To set the current encryption key, just enter the key in hex digits as
XXXX-XXXX-XXXX-XXXX or XXXXXXXX. To set a key other than the current
key, prepend or append [index] to the key itself (this won't change
which is the active key). You can also enter the key as an ASCII string
by using the s: prefix. Passphrase is currently not supported.
To change which key is the current active key, just enter [index] (with-
out entering any key value).
off and on disable and reenable encryption, open set the system in open
mode (accept non-encrypted packets) and restricted discard non-encrypted
packets.
If you need to set multiple keys, or set a key and change the active
key, you need to use multiple key directives. Arguments can be put in
any order, the last one will take precendence.
Examples :
iwconfig eth0 key 0123-4567-89
iwconfig eth0 key sassword [2]
iwconfig eth0 key [2] open
iwconfig eth0 key off
iwconfig eth0 key restricted [3] 0123456789
iwconfig eth0 key 01-23 key 45-67 [4] key [4]

and it should be fine to set these in the /etc/pcmcia/wireless.opts file.