dima_riabets,
если собрать все значения отмеченных инпутов то можно так
<!DOCTYPE HTML>
<html>
<head>
<title>Untitled</title>
<meta charset="utf-8">
<script type='text/javascript' src='http://code.jquery.com/jquery-1.10.2.js'></script>
<script>
$(function () {
$('div.filterBlock').on('click', 'input', function () {
var values = $.map($('div.filterBlock input:checked'), function (el) {
return el.value
})
$('input[name="pull"]').val($.makeArray(values))
});
});
</script>
</head>
<body>
<input type="text" name="pull" style="width: 100%; font-size: 11px; position: relative;" maxlength="150">
<div class="filterBlock" style="height:200px;width:200px;overflow:auto;white-space:nowrap;">
<input type="checkbox" name="filter2" value="1" id="fk21"><label for="fk21">1</label><br>
<input type="checkbox" name="filter2" value="1" id="fk22"><label for="fk22">1</label><br>
</div>
</body>
</html>