If what you mean is indeed a property of an OPC item, then subscribing to it is not directly possible, and it has to be done by repeatedly obtaining its value - unless the server also has a correspnding OPC item for that property; if this was the case, you would find its ItemID from BrowseProperties call, and the value of ItemId of DAPropertyElement.
If you mean subscribing to a regular OPC item that is a bit - most likely, of VT_BOOLEAN type, then subscribing to it is certainly possible, and does not differ from doing so with any other data type. There are several example for this in the Bonus Pack, also depending on the programming language and type of environment your are using (such as Windows Forms, ASP.NET ...). E.g. for WinForms in C#, following examples in the Bonus Pack contain item subscription code:

EasyOpcDaNetDemo1
HmiScreen
SubscribeToMany

If you let me know which of the above cases you are trying to resolve, and some more details (programming language, VS version, hosting environment, ItemID etc.), I can point you to right example or provide pieces of code.
Best regards,
Zbynek Zahradnik