update lightbox on the fly

May i update lightbox from window and throws ajax send to map_field values ???

There is no API, which can alter values in lightbox on the fly.
But

a) you can alter initial values, or final values by intercepting related event handlers, and altering values of event object

or

b) you can create a custom form section, instead of default one - in such case you can assign some html ids for the elements, and use that ids to alter elements on the fly.

i want to load form or xml into map-field.

Form in ul or html, or data with xml.

What you suggest, and what functions to operate ???

i see function update may i use it or not ??

sorry, but it is not clear which use-case you need to implement.