I think you're better off using the Half-Fiend Template in 3ed's Monster Manual. It better captures the fact that it's not a race so much as an amalgamation of two races. If you're concerned about power levels, you could always go with the Tiefling instead, also in the MM.
While the Alu-Fiend and Cambions are nice to see for nostalgic reasons (well, I don't care for their representation in ToH), I've never cared for the limited degree of customization.