How to hash Membership user passwords

Hello, I have this ASP.NET app working ok, now I need to add users and passwords from a WinForms App directly to the sql asp membership database and I'm having problems to find a way to encrypt passwords correctly. I followed the solution here: http://forums.asp.net/t/1336657.aspx but it didn't work for me (generated passwords are different from the ones in the db)
This is a portion of my web.config:
<membership defaultProvider="DefaultMembershipProvider"> <providers> <add name="DefaultMembershipProvider" type="System.Web.Providers.DefaultMembershipProvider, System.Web.Providers, Version=1.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" connectionStringName="DefaultConnection" enablePasswordRetrieval=&q ...