It depends on what version of Asp.net you are using in Asp.net 2.0 it is easy because of the introduction of the Nullable <T> because it also takes boolean, it is very hard in 1.1. Try the link below for Nullable solutions including the bool. Hope this helps.
http://www.codeproject.com/cs/database/NullableReaders.asp
Kind regards,
Gift Peddie