The background sync should kick in every 20 minutes, regardless of what folder you happen to be viewing at the time.

Create VbaProject.OTM - VBA project for Outlook in C:\Documents and
Settings\%username%\Application Data\Microsoft\Outlook\

Open Outlook and press Alt+F11 to open VbaProject.OTM

Paste this code into ThisOutlookSession Startup event

=====================================================
Private Sub Application_Startup()

' NAME: WSS StsSyncAddOn
'
' AUTHOR    : Shilov Pavel sorgy@hotbox.ru
' DATE      : 14.02.2006
' VERSION   : 1.0.1
'
' COMMENT: Script to sync WSS contact lists. This script must be executed
'           on Outlook startup. It opens all WSS contact list folders in
Outlook
'           and sync data with SharePoint
'

   Dim strMsg1, strMsg2 As String
   Dim olApp As New Outlook.Application
   Dim oNS As Outlook.NameSpace
   Dim fldFolder As Outlook.MAPIFolder
   Dim fldFolder1 As Outlook.MAPIFolder
   Dim expContacts As Outlook.Explorer
   Dim Response
   Dim arrAppVer
   On Error Resume Next
   arrAppVer = Split(olApp.Version, ".")
   If CInt(arrAppVer(0)) < 11 Then Exit Sub
       strMsg1 = "Outlook should synchronize SharePoint contact lists." &
Chr(13) & Chr(10) & "This can take some minutes" & Chr(13) & Chr(10) &
"Continue?"
       strMsg2 = "Contact lists have been synchronized successfully."
   
   Set oNS = olApp.GetNamespace("MAPI")
   For Each fldFolder In oNS.Folders
       If fldFolder.IsSharePointFolder = True Then
           If fldFolder.Folders.Count < 1 Then Exit Sub
           Response = MsgBox(strMsg1, vbOKCancel + vbInformation +
vbDefaultButton2, "WSS StsSyncAddOn")
           If Response = vbOK Then
               For Each fldFolder1 In fldFolder.Folders
                   Set expContacts = fldFolder1.GetExplorer
                   expContacts.Activate
                   expContacts.Close
               Next
               Response = MsgBox(strMsg2, vbOKOnly + vbInformation, "WSS
StsSyncAddOn")
           End If
       End If
   Next
   On Error GoTo 0
End Sub

=====================================================

Sign code with digital signature from your MS CertSrv of your Domain

Use this script to distribute VbaProject.OTM

'==========================================================================
'
' NAME: VBA OTM distribute
'
' AUTHOR: Shilov Pavel , sorgy@hotbox.ru
' DATE  : 21.02.2006
' VER : 1.0.1
' COMMENT:
'
'==========================================================================
On Error Resume Next
    Dim strPath, strPathToCopy, strFileName, strOfficeKey, res, WSHShell
    strPath = "%Yuor share folder%"   
    strFileName = "Install.cmd"
    strOutlookFName1 = "VbaProject.OTM"   
    strOutlookFName2 = "outcmd.dat"   
    strOfficeKey =
"HKEY_CURRENT_USER\Software\Microsoft\Office\11.0\Outlook\UserInfo\UserInfo"
    set WSHShell = WScript.CreateObject("WScript.Shell")       
    strAgent = WSHShell.RegRead (strOfficeKey)
    If Err = 0 Then
        Set oFS = CreateObject("Scripting.FileSystemObject")
        Set oDir = oFS.GetFolder(WSHShell.ExpandEnvironmentStrings("%APPDATA%") &
"\Microsoft\Outlook\")
        Set oFiles = oDir.Files
        For Each of In oFiles
            If (of.Name = strOutlookFName1) Or (of.Name = strOutlookFName2) Then
                of.Name = Left(of.Name,Len(of.Name)-3) & "back"
            End If
        Next
        cmd = CHR(34) & strPath & strFileName & Chr(34)
        res = WshShell.Run(cmd,0,True)
    End If
    Set WshShell = Nothing
On Error Goto 0

=======================================================
Install.cmd

Copy %YourShareFolder%\VbaProject.OTM "%APPDATA%\Microsoft\Outlook\" /y
Copy %YourShareFolder%\outcmd.dat "%APPDATA%\Microsoft\Outlook\" /y