Alternatively you might be able to register specific protocol handlers on your systems which allow you to launch an existing terminal emulator like PuTTY. See this site for some information on how to do this with Firefox.
After registering a protocol (e.g. console://) then you should be able to just insert links like
console://192.168.1.1 in your HTML documents in order to allow clients with properly registered console:// protocol handler to connect by launching the local PuTTY terminal emulator with correct parameters.