Yes, I know this is coming very late. Let me just share how I achived the same purpose:
Apperyio("popup_name").popup("open",{positionTo:position})
popup_name is the name of your popup.
positon is the desired position of the popup. In this particular case of listitems, I computed my position as follows:
$(this).find('.listitem-entry-initials')[0]
where
$(this): refers to the clicked element of the list
listitem-entry-initials: is a classname assigned to a component of the list entries. In my case, I used a label component. You may also want to play with tolerance option so you can properly place the popup as disired, especially if you are using arrows. tolerance level can be set on the appery builder or you may choose to supply it with the options. see https://demos.jquerymobile.com/1.2.0/...
See sample screenshot below: