I've been spend hours and hour searching for code like this, finally I was make this works (yeah!), I hope this wolud be useful for somebody... = )
struser= "your_user"
strpwd= "your_user_pwd"
strdomain= "your_domain.com"
strvaliddn= "uid=" & struser & ",ou=People,o=" & strdomain & ",o=isp"
strservername="your_server_name_or_ip:389"
Set conn = CreateObject("ADODB.Connection")
conn.Provider = "ADsDSOObject"
conn.Properties("User ID") = struser
conn.Properties("Password") = strpwd
conn.Open "ADs Provider", strvaliddn, strpwd
Set objldap = CreateObject("ADODB.Command")
objldap.ActiveConnection = conn
on error resume next
objldap.CommandText = "SELECT cn FROM 'LDAP://" & strservername & "/" & strvaliddn & "' "
set rs = objldap.Execute
If rs.eof or rs.bof then
authresult=""
else
authresult="Y"
end if
set objldap=nothing
set rs=nothing
Set conn=nothing