No it is not possible. jQuery should add an "add" method to accordion like they have for tabs:
//save state
var state = $("#accordion").accordion( "option", "active" );
//add accordion item, destroy then re-create
$("#accordion").append("<h3></h3><div/>").accordion("destroy").accordion();
//set state
$("#accordion").accordion( "option", "active", state );
Wrap it in a nice method, extend accordion, submit a patch, etc. I didn't test this but it should work. You might have to adjust the state value if the tab was inserted before the active accordion item, instead of appended to the end.
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