I've downloaded the Windows 64-bit Litecoin mining software as provided from http://pool-x.eu/gettingstarted

I'm trying to run the miner from behind a firewall. My browser uses an HTTP proxy to get to the internet, and as I understand it I should be able to use a similar method to connect my Litecoin miner to a pool.

So far, I've modified the file start.console.bat from:

@echo off

START /LOW /B minerd.exe --algo scrypt --url http://litecoinpool.org:9332/ --userpass username.1:1 --threads 4 -r -1 -s 5

to:

@echo off
set HTTP_PROXY=http://myproxyserver:myport
START /LOW /B minerd.exe --algo scrypt --url http://litecoinpool.org:9332/ --userpass myusername.1:mypassword --threads 4 -r -1 -s 5

I've substituted my values in to take the place of the following values: myproxyserver myport 9332 myusername.1 mypassword

When I try using the port my browser uses for the proxy server (for both port values), I get this output when I run it (and it spits out another error every 30 secs):

[2012-07-07 13:57:48] HTTP request failed: The requested URL returned error: 503

[2012-07-07 13:57:48] json_rpc_call failed, retry after 30 seconds
[2012-07-07 13:57:48] 1 miner threads started, using 'scrypt' algorithm.

Should the port number for the proxy and for the mining script be the same? What settings can I use to get my miner working?