Though I haven't worked on the same myself, the answer is yes, it is possible. The reason for that is that IPSec is an open standard and supported by both the boxes in question. Some minor issue do crop up such as the system message "Failure during phase 1 rekeying attempt due to collision" followed by a quick disconnect and reconnect of the tunnel. Even these issues can be sorted out using simple steps such as setting the rekeying interval. You'll need to be careful about these issues.