I can't speak specifically to the Firebox 700 firewall and it's capabilities. However, knowing that the PIX firewall will establish IPsec connections following the IPsec RFC, there should no direct issues with any basic IPsec connectivity. I do know that the PIX will interoperate cleanly with other VPN devices which illustrates this point.
My advice to you would be to make sure you understand the IPsec protocol options and use that expertise to work your way through the product specific terminology...
Good Luck!
Marcus