<embed pluginspage="http://www.sidmusic.org/sidplay/mac/" src="Elysion.sid" type="audio/prs.sid" width="256" height="64">
The above should cause the plug-in to get active.
You can set the size for the oscilloscope output, or you can add the add the hidden argument to disable the output.
Please use the "Get SIDPlug" icon somewhere one your page to link to the SIDPlug download page.

Right now you should be listening to "Elysion" by Steven Diemer.
Ask your internet service provider to set up the following file type on their HTTP server. You will then be able to offer one-file sidtunes from your home page without problems:
MIME type: audio/prs.sid Extension: .sid File type: SID Music
The use of the MIME types audio/x-psid, audio/x-sidtune and the ".dat" file extension is deprecated.
Currently supported plug-in arguments are:
HIDDEN=true or false
to show/hide the plugin (i.e. the oscilloscope display).
Default: true
The following options are currently only supported by the Mac OS X version of SIDPlug, on other operating systems, they will be ignored.
COLOR=#rrggbb
to specify the color of the oscilloscope beam.
Default: a bright cyan
If you pass illegal values to an argument, SIDPlug will fall back to defaults. The order of the arguments is not important. If an argument is multiply used, the last occurence is taken.