Hey,
when defining an entry in the PaletteProvider you can provide custom html. If you for example create a div containing text, this is what is displayed in the palette. You probably have to do some CSS styling though:
'my-entry': {
group: 'event',
html: '<div class="entry">My Text</div>',
action: {
click: function(event) {
var shape = elementFactory.createShape({ type: 'bpmn:StartEvent' });
create.start(event, shape);
}
}
}