It's kind of difficult, unless you create a property hardcoded in your class, but that'snot what you want of course.
To get the custom fields show up in a grid as columns, propertydescriptors for these fields have to be created at runtime. I'm not sure what you're using, selfservicing or adapter. In selfservicing it's a little 'easier' than in adapter.
In selfservicing a PropertyDescriptorFactory is used for collections. See FactoryClasses\PropertyDescriptorFactory.cs. This class produces the propery descriptors in GetPropertyDescriptors. If you modify that class (for example by writing your own or modifying the template) you can produce different properties and for example produce propertydescriptors for your custom properties.
Keep in mind that PropertyDescriptorFactory will be removed in v2.0.