InDesign CS4: Can't get at page items in a group

I can’t for the life of me figure out how to iterate through all the grouped items in a library item I’ve placed in ID CS4.

Here’s the section of the script:

tell application "Adobe InDesign CS4"
	set myDocument to active document
	set myPage to page 2 of myDocument
	set active page of layout window 1 to myPage
	set assetPlacer to place asset asset "3_12:13" of library "Logowear_Lib.indl" on myDocument
	move assetPlacer to myPage
	tell myDocument
		tell myPage
			set label of (every item of all page items of page item assetPlacer whose label = "CW1") to "TEST!"
		end tell
	end tell
end tell

The real deal is a little more complicated. I’m basically placing a library item that is a group of text frames and pre-labeled picture frames and then iterating through the picture frames in that group and giving them new labels. I have no trouble making this work with page items using something like the line below, but I can’t seem to get at just the items in the group.

set label of (object reference of every item of all page items of page pageNum of myDocument whose label = oldLabelName) to newLabelName