Here is an appender config that I've used, which calls a stored procedure directly. It can't call your DAL code, but it can call the stored proc out of the box.
<appender name="AdoNetAppender" type="log4net.Appender.AdoNetAppender">
<bufferSize value="1" />
<threshold value="INFO" />
<connectionType value="System.Data.SqlClient.SqlConnection, System.Data, Version=1.0.3300.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" />
<connectionString value="data source=<your_server>;initial catalog=<database_name>;User ID=<user_id>;Password=<pwd>" />
<commandText value="dbo.spLogInsert" />
<commandType value="StoredProcedure" />
<parameter>
<parameterName value="@log_date_utc" />
<dbType value="DateTime" />
<layout type="log4net.Layout.RawTimeStampLayout">
<conversionPattern value="%utcdate" />
</layout>
</parameter>
<parameter>
<parameterName value="@log_date_local" />
<dbType value="DateTime" />
<layout type="log4net.Layout.RawTimeStampLayout">
<conversionPattern value="%date" />
</layout>
</parameter>
<parameter>
<parameterName value="@thread" />
<dbType value="String" />
<size value="255" />
<layout type="log4net.Layout.PatternLayout">
<conversionPattern value="%thread" />
</layout>
</parameter>
<parameter>
<parameterName value="@log_level" />
<dbType value="String" />
<size value="50" />
<layout type="log4net.Layout.PatternLayout">
<conversionPattern value="%level" />
</layout>
</parameter>
<parameter>
<parameterName value="@logger" />
<dbType value="String" />
<size value="255" />
<layout type="log4net.Layout.PatternLayout">
<conversionPattern value="%logger" />
</layout>
</parameter>
<parameter>
<parameterName value="@message" />
<dbType value="String" />
<size value="4000" />
<layout type="log4net.Layout.PatternLayout">
<conversionPattern value="%message" />
</layout>
</parameter>
<parameter>
<parameterName value="@exception" />
<dbType value="String" />
<size value="2000" />
<layout type="log4net.Layout.ExceptionLayout" />
</parameter>
<parameter>
<parameterName value="@server" />
<dbType value="String" />
<size value="2000" />
<layout type="log4net.Layout.PatternLayout">
<conversionPattern value="%property{log4net:HostName}"/>
</layout>
</parameter>
</appender>