How would I implement undo functionality in a BO for custom data properties? They are read/write and bindable. Specifically, I want my custom properties to undo when BO.undo is called.

I'm talking custom properties, defined in the main BO file (not the BO Mapper generated designer file), with the reflectionpropertydescriptor thingy to get binding to work. I'm reading and writing to another table (not sure its a good idea, but sure is easy ) Anyway to get undo (SF undo) to work with these?

If you are updating a table other than the internal data table (CurrentDataTable, CurrentRow, CurrentView...take your pick ) then you will have to handle this in the AfterUndo method yourself.  If you have an ADO.NET data table just reject the changes:

OK. That's what I needed to known. Thanks!