Thank you, perfect!
I've added the <%SELECTORS%> tag to the calendar input form in:
<component_name>/dom/html/form/input/calendar.php
So the variable $html is now defined (from line 143) as....
$html = self::calendar(
$formatedDate,
$this->getInputName(),
$this->getInputId(),
$this->dateFormat,
'class="' . $this->getDomClass() . '"<%STYLE%><%SELECTORS%>',
The link to the datepicker+1 is precisely what I'm trying to do too.
As a PHP and jQuery noob, j-cook has proved
really useful - so thanks very much for the help.