Siva,
There's a sample HTTP Receive adapter included in the SDK with BizTalk 2006, though not with 2004. It's not a high performance adapter, but it's very simple, and it shouldn't be too hard to back port it to 2004 if you want, and modifying it shouldn't be hard to do what you want.
If you're feeling lazy, then you could just build a simple ASP.NET page that uses the SubmitDirect sample adapter included in the SDK (this one is available in 2004 as well) to send the message over to biztalk. It would certainly be faster to do if you need something put together quickly.