Change the GetSmartParams (or whatever it is) function to set the values yourself.
Code:
SetLength(Params, 2);
Params[0] := 'http://__________.runescape.com/';
Params[1] := ''; // what is after the last "/" in the url
Go to "http://oldschool.runescape.com/slu" and just find a world (choose the best world would work).
Look at the url and separate it into each parameter, as shown above.
The EOC url looks something like "http://world1.runescape.com/,123abcd463", but as you can tell, there is no comma in the url for old school.
Make sure you remove the "," that is concatenated to the Params[1] when SMART is being spawned, or else it will not work.
Also, reduce the height (the second integer) by 50 pixels, should be 503 I think.