Do you mean to put in front of ASL or at another location and create a tunnel back to ASL? In front of ASL, don't need, ASL does it all. At the other end you could just use another ASL. There are routers out there that claim IPSEC but I haven't tried them and would be leary about buying something that will be abandoned next year as they always do. Check Linksys though, they have one. But again they will abandon it next year and only support the latest and greatest thing that barely works. Easier to upgrade ASL.
my intention is to put it to another location and create a tunnel back to asl. after a long search i found a good product. im going to test if it will work. it is maybe very wise to use a asl but a hardware vpn is handy.