The TreeList columns are not binding containers (the TreeList rows are) and that is the reason you cannot use Eval/Bind expressions for column properties. For the template columns you can inject binding expressions as part of their header, item, etc. templates. Let me know if I am missing something here.
For the HyperLink TreeList column in particular, you may consider using its DataTextField to specify column in the source from which the text values will be populated.
the Telerik team