Basic support for Custom BigDialogBoxes has been added. You can put them in BigNPCBox.wil and use OPENBIGDIALOGBOX Number to use it. For example to open the normal BigDialogBox use OPENBIGDIALOGBOX 0. iJam has some examples, hopefully he'll post them.

use #ACT OPENBIGDIALOGBOX 0 - 3
simply export them and change the shape and size to
whatever you want really, or make your own ;) 