Hi,
NetBSD requires 486 instructions *and* x87 FPU; MATH_EMULATE option was removed back in 2008 before 5.0 was released: http://cvsweb.netbsd.org/bsdweb.cgi/src/sys/arch/i386/i386/Attic/math_emulate.c?hideattic=0 According to Wikipedia, Cx486DLC lacks internal FPU. This should be why it does not work. Does the system have slot for external FPU?
The board has an FPU installed (ULSI "DX/DLC"), and even though the dmesg doesn't show it, NetBSD makes use of it as evidenced by pkgsrc/benchmarks/flops, plus sysctl gives machdep.fpu_present = 1.
Hmmm... John