Snow Leopard was in the second partition of that HD? I hope so, then you can add that 70 gigs to Lion. Then:

1) Make sure in your BIOS to have SATA mode set up as AHCI (or RAID, if you don't have AHCI as an option);

2) Boot in Lion. Disconnect the Win7 HD;

3) Reinstall Chameleon. Use the latest revision.

4) Reconnect the Win7 HD;

5) Enjoy.

P.S.: I'm assuming that all your HDs are SATA. If one or both of them are PATA, forget it.