How to read from Serial port in a webpage

I want to design a webform that user should fill some fields. The value of one field should be read from Serial port (COM1) of client computer which a special hardware is connected to it and the user presses the Send to PC key of the hardware when filling the form.

How i can listen to COM1 port in my webpage and get the value of COM1 and place it in the web form automatically?

I heard that ActiveX controls can do this but it is compatible only with IE (right?). The other option is Java applets.

I want a simple solution which be compatible with (at least) IE/Firefox/Opera.

I the server-side i can have ASP or PHP but i am appreciate if you give a solution for each.

UPDATE:

We can tell clients to change their security settings to accept our ActiveX/applet.

It is also possible for us to tell clients to install a custom program which runs as a service and reads from Serial port.

The problem is the read data should be entered to the webform automatically and immediately.

The java applet is a good idea, but the client have to install JRE which is large in size.

Is there any other option?