Thanks – the TJSDialog uses a TForm on XP to emulate the Vista TaskDialog, so using the below worked to show the dialog as normal:
sSkinManager1.SkinningRules := sSkinManager1.SkinningRules – [srStdForms];
..show dialog
sSkinManager1.SkinningRules := sSkinManager1.SkinningRules + [srStdForms];
Now I need to learn how I can skin the dialog so that it matches the current skinning. I might need to just replace the TJSDialog component and go back to regular dialog boxes.