Habpanel slider value transformation

is it possible to create a custom habpanel slider widget that allows a data transformation of the value to be displayed. This is possible in a sitemap as below. The transform converts the value in minutesoftheday to time.

Setpoint item=TimerOn label="TimerOn [JS(numberToClock.js):%s]" minValue=0 maxValue=1440 step=15

I can write a rule to update another item with the transformed value and display in the dummy widget but does not really work as the value only updates when a value is set a value vs dynamically as the slider is moved.