[zdevil]

Thanks!
Just tried your solution.
I was using

wget http://www.feedbooks.com/newsstand/subscription?user=zdevil&password=MYMD5HASHblahblahblah

Then I got this: (actual username and password hidden of course)

[1] 4838
MacBook:~/Desktop/RSS USERNAME$ --23:14:56--  http://www.feedbooks.com/newsstand/subscription?user=USERNAME
           => `subscription?user=USERNAME'
Resolving www.feedbooks.com... 91.121.16.74
Connecting to www.feedbooks.com|91.121.16.74|:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: unspecified [application/xml]

    [ <=>                                                                         ] 95            --.--K/s             

23:14:56 (5.66 MB/s) - `subscription?user=USERNAME' saved [95]

Then the terminal stops here without downloading anything or returning to prompt.

Then I found a small file called subscription?user=USERNAME and saw this:

<?xml version="1.0" encoding="UTF-8"?>
<newsstand>
  <status>Login Error</status>
</newsstand>

What to do?