I'm merely the Biml scribe and the source article can be found here.http://ow.ly/Q18my

                    <DerivedColumns Name="DER - Biml version of SSIS expressions by bonk">
                        <Columns>
                            <#* Strings *#>
                            <!-- Filename from fully qualified pathstring -->
                            <Column Name="FileName" DataType="String" Length="200" ReplaceExisting="false">RIGHT([FilePath],FINDSTRING(REVERSE([FilePath]),"\\",1) – 1)</Column>
                            <!-- Folderpath from fully qualified pathstring -->
                            <Column Name="FolderPath" DataType="String" Length="200" ReplaceExisting="false">SUBSTRING([FilePath], 1, LEN([FilePath]) – FINDSTRING(REVERSE([FilePath] ), "\\" ,1 ) + 1)</Column>
                            <!-- Foldername from fully qualified pathstring -->
                            <!-- This is only for SSIS2012 and onwards. The TOKEN and TOKENCOUNT expressions are not in prior versions of SQL Server -->
                            <Column Name="FolderName2012" DataType="String" Length="200" ReplaceExisting="false">TOKEN[FilePath],"\\",TOKENCOUNT([FilePath],"\\") – 1)</Column>
                            <!-- For prior versions of SQL Server -->
                            <Column Name="FolderName2008" DataType="String" Length="200" ReplaceExisting="false">SUBSTRING([FilePath],LEN([FilePath]) – FINDSTRING(REVERSE([FilePath]),"\\",2) + 2,(LEN([FilePath]) – FINDSTRING(REVERSE([FilePath]),"\\",1)) – (LEN([FilePath]) – FINDSTRING(REVERSE([FilePath]),"\\",2)) – 1)</Column>
                            <!-- Replace empty strings -->
                            <!-- With SQL Server 2012 the new REPLACENULL function was implemented, making it alot easier to replace empty values. -->
                            <Column Name="ColumnName1" DataType="String" Length="200" ReplaceExisting="true">REPLACENULL([ColumnName1], "Replace Value")</Column>
                            <!-- For earlier versions of SQL Server -->
                            <Column Name="ColumnName2" DataType="String" Length="200" ReplaceExisting="true">ISNULL([ColumnName2]) ? "Replace Value" : [ColumnName2]</Column>

                            <#* Date and time *#>
                            <!-- Date from datetime -->
                            <Column Name="Date1" DataType="Date" ReplaceExisting="false">(DT_DATE)(DT_DBDATE)@[User::datetimeVariable]</Column>
                            <Column Name="Date2" DataType="Date" ReplaceExisting="false">(DT_DATE)(DT_DBDATE)[datetimeColumn]</Column>
                            <Column Name="Date3" DataType="DateTime" ReplaceExisting="false">(DT_DBTIMESTAMP)(DT_DBDATE)GETDATE()</Column>
                            <!-- Time from datetime -->
                            <Column Name="Time1" DataType="AnsiString" Length="8" CodePage="1252" ReplaceExisting="false">(DT_STR,8,1252)(DT_DBTIME)@[User::datetimeVariable]</Column>
                            <Column Name="Time2" DataType="AnsiString" Length="8" CodePage="1252" ReplaceExisting="false">(DT_STR,8,1252)(DT_DBTIME)[datetimeColumn]</Column>
                            <Column Name="Time3" DataType="AnsiString" Length="8" CodePage="1252" ReplaceExisting="false">(DT_STR,8,1252)(DT_DBTIME)GETDATE()</Column>
                            <!-- First day of the current month -->
                            <Column Name="FirstDay1" DataType="DateTime" ReplaceExisting="false">DATEADD("d", -DAY(GETDATE()) + 1, GETDATE())</Column>
                            <Column Name="FirstDay2" DataType="DateTime" ReplaceExisting="false">(DT_DBTIMESTAMP)(DT_DBDATE)DATEADD("d", -DAY(GETDATE()) + 1, GETDATE())</Column>
                            <!-- Last day of the current month -->
                            <Column Name="LastDay1" DataType="DateTime" ReplaceExisting="false">DATEADD("d", -DAY(GETDATE()), DATEADD("m", 1, GETDATE()))</Column>
                            <Column Name="LastDay2" DataType="DateTime" ReplaceExisting="false">(DT_DBTIMESTAMP)(DT_DBDATE)DATEADD("d", -DAY(GETDATE()), DATEADD("m", 1, GETDATE()))</Column>
                            <Column Name="LastDaySeconds" DataType="DateTime" ReplaceExisting="false">DATEADD("s", -1,DATEADD("d", -DAY(GETDATE()) + 1, DATEADD("m", 1, (DT_DBTIMESTAMP)(DT_DBDATE)GETDATE())))</Column>
                            <!-- Weeknumber of the month --> 
                            <Column Name="WeekNumber" DataType="Int32" ReplaceExisting="false">(DATEPART("ww",[YourDate]) – DATEPART("ww",DATEADD("d", -DAY([YourDate]) + 1, [YourDate]))) + 1</Column>
                            <!-- Datetime as concatenated string -->
                            <Column Name="DateToString" DataType="String" Length="20" ReplaceExisting="false">(DT_STR, 4, 1252)DATEPART("yyyy", @[System::StartTime]) + RIGHT("0" + (DT_STR, 2, 1252)DATEPART("mm", @[System::StartTime]), 2) + RIGHT("0" + (DT_STR, 2, 1252)DATEPART("dd", @[System::StartTime]), 2) + RIGHT("0" + (DT_STR, 2, 1252)DATEPART(“hh”, @[System::StartTime]), 2) + RIGHT("0" + (DT_STR, 2, 1252)DATEPART("mi", @[System::StartTime]), 2) + RIGHT("0" + (DT_STR, 2, 1252)DATEPART("ss", @[System::StartTime]), 2)</Column>
                        </Columns>
                    </DerivedColumns>