This should work for you. I do this on a website of mine.
<%
Dim objJet, objFSO, objFile, strDBFile, strDestFile
Dim strConnect, strDestConnect
strDBFile = Server.MapPath("/db/ShopDb.mdb"

strDestFile = Server.MapPath("/db/dest.mdb"

strConnect = "PROVIDER=Microsoft.Jet.OLEDB.4.0;DATA SOURCE=" & Server.MapPath("/db/ShopDB.mdb"

strDestConnect = "PROVIDER=Microsoft.Jet.OLEDB.4.0;DATA SOURCE=" & Server.MapPath("/db/dest.mdb"

Set objFSO = Server.CreateObject("Scripting.FileSystemObject"

Set objFile = objFSO.GetFile(strDBFile)
Response.Write "<tr><td>Database file size <b>before</b> compatcing: "& FormatNumber(objFile.Size, 0) &" bytes</td></tr>"
Set objFile = Nothing
Set objFSO = Nothing
Set objJet = Server.CreateObject("JRO.JetEngine"

objJet.CompactDatabase strConnect, strDestConnect
Set objJet = Nothing
Set objFSO = Server.CreateObject("Scripting.FileSystemObject"

Set objFile = objFSO.GetFile(strDBFile)
objFile.Delete
objFSO.MoveFile strDestFile, strDBFile
Set objFile = objFSO.GetFile(strDBFile)
Response.Write "Database file size <b>after</b> compatcing: "& FormatNumber(objFile.Size, 0) &" bytes"
Set objFile = Nothing
Set objFSO = Nothing
%>