Download hOSDock.dll, i use this myself for several dialogs to dock, and it's ideal, once you've done that make an alias to define the filepath
this is mine..
alias _hos { dll system\hOSDock.dll) $1- }

when you've done that, you need to add the docking info into the
INIT part of the dialog
on *:DIALOG: notify :INIT:*: {

i usually put it somewhere near the bottom
_hOS Dock notify right 1