Hi,
try this untested code..
open admin_functions.php and find
echo "<b>URL:</b><br><input type=\"text\" name=\"remote_".$name."\" value=\"".$value."\" size=\"".$textinput_size."\">";
in
show_upload_row function.
replace it with the following one..
echo "<b>URL:</b><br><input type=\"text\" name=\"remote_".$name."\" value=\"http://site.com/test.jpg\" size=\"".$textinput_size."\">";
change ur desired .. site name ..
Thanks,