checkboxtree value in 6.5.2

I would like to render my checkboxtree value just like the debug view does (a comma delineated list).

How would I go about writing that in velocity/jexl?

#set($items = $sys.item.getProperty(“opregion”).getValues())

#foreach($item in $items)
$item.String
#end

same way as the sysDropDownMultiple. Read in the post below.