Don't know if you are still looking for an answer. But one option would be to create an editing task or extension. If you work with a task you could connect to the closing event handler on the EditAttributesDialog
m_ead = new EditAttributesDialog(m_feature);
m_ead.Text = "Collect Feature";
m_ead.Closing += new System.ComponentModel.CancelEventHandler(m_ead_Closing);
The in the closing event you could loop through the various fields in the feature and implement your checks. If a check fails then you could show a message dialog with the error and then specify
e,Cancel = true;
Which will return the user to the editattributesdialog.
