VPN routing works with non-Check-Point VPN endpoints, but they need to be within the same VPN community.
You might be able to use per-community VPN domains to tell the community with ASA 1 that your Check Point box's encryption domain includes ASA 2's domain, and the community with ASA 2 that your Check Point box's encryption domain includes ASA 1's domain. I haven't personally tried this before, and I can think of a few reasons it might not work. If you can't put both ASAs into the same VPN community, that's your best bet.
You could also move away from domain-based VPNs entirely and use route-based. That lets you set up a tunnel interface on the firewall to each peer. Then routing works just like it does with any other interface.