I decided to submit "box" and check out the results.

POST /entrez/query.fcgi?CMD=Pager&DB=PubMed HTTP/1.1
Referer: http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?CMD=Search&DB=P
+ubMed
Accept-Language: en-us
Content-Type: application/x-www-form-urlencoded
Accept-Encoding: gzip, deflate
User-Agent: Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1)
Host: www.ncbi.nlm.nih.gov
Content-Length: 296
Connection: Keep-Alive
Cache-Control: no-cache
Cookie: LB-Hint-PubMed=0SlUKGwUky2Rn3_3B5G; WebEnv=09ZSqwvMGrYSnbQNfTt
+bZquWN8EWwljKW624FLtMbtqQuh4E9eSM5k

WebEnv=09ZSqwvMGrYSnbQNfTtbZquWN8EWwljKW624FLtMbtqQuh4E9eSM5k&db=PubMe
+d&orig_db=PubMed&term=box&cmd=&cmd_current=&query_key=4&dopt=DocSum&d
+ispmax=20&sort=&SendTo=Text&textpage=1&inputpage=2&CrntRpt=DocSum&sho
+wndispmax=20&page=0&dopt1=DocSum&dispmax1=20&sort1=&SendTo1=Text&text
+page1=1&inputpage1=
[download]

And the response header:

HTTP/1.1 200 OK
Date: Mon, 30 Jun 2003 06:59:19 GMT
Server: Apache
Set-Cookie: LB-Hint-PubMed=0y_fmGJi19Cg5T8fvAR; domain=.nlm.nih.gov; p
+ath=/; expires=Mon, 30-Jun-2003 07:04:19 GMT
Set-Cookie: WebEnv=0XdSUuxNcjqgflC3VlxDhofrq5G4V7_aVtA9dsKTtm3Bq-wvz1O
+M5U; domain=.nlm.nih.gov; path=/; expires=Mon, 30-Jun-2003 14:59:19 G
+MT
Content-Type: text/html
Via: 1.1 www.ncbi.nih.gov
X-Cache: MISS from www.ncbi.nih.gov
Keep-Alive: timeout=5, max=100
Connection: Keep-Alive
Transfer-Encoding: chunked
[download]

So what can we tell about all this mumbo jumbo? A form is posted to /entrez/query.fcgi?CMD=Pager&DB=PubMed. Notice that the site uses cookies and the cookie is changed on every access to the page. Also, there are 22 fields you need to submit (everything should be submitted as is unless it has an arrow pointing to it):

WebEnv= <---Same as what's in your cookie, changes every time
db=PubMed
orig_db=PubMed
term=   <---Search term
cmd=
cmd_current=
query_key=  <---Need to extract out of the first page (server seems to
+ enumerate searches...this will eventually get wiped out if you wait 
+too long)
dopt=DocSum
dispmax=20
sort=
SendTo=Text
textpage=   <---Current page numerically
inputpage=  <---Page we're going to
CrntRpt=DocSum
showndispmax=20
page=       <---Page prior to textpage
dopt1=DocSum
dispmax1=20
sort1=
SendTo1=Text
textpage1= <---Always seems to be the same as textpage
inputpage1=
[download]

Now you're probably wondering to yourself, "gee antirice, is that all there is to it?" To tell you the truth I really don't know. I captured a total of five transactions with three different search terms and compared them to see what was different and what correlated to what. I was just doing this to help you since I run into this quite frequently and the Javascript module works ok but not always as well as one would hope.

In case you were wondering, I captured everything using a program called ethereal. I find it to be a very handy tool when trying to mimic any sort of transaction without documentation. Please note what we have here is a hack at best. If they really wanted you to do this in an automated fashion, they probably would have provided a documented interface to the search engine. Of course, it's the government and they may have not gotten around to it yet.