I've tried to achieve it like the following:
C_COMPILER=mipsel-linux-uclibc-gcc make PLATFORM=linux
The compiler is from my MIPS toolchain and can be found through the PATH. It fails with this error:
mipsel-linux-uclibc-gcc -fno-strict-aliasing -fwrapv -DHAVE_CHICKEN_CONFIG_H -DC_ENABLE_PTABLES -c apply-hack.x86-64.S -o apply-hack.x86-64.o
apply-hack.x86-64.S: Assembler messages:
apply-hack.x86-64.S:36: Error: unrecognized opcode `subq $8,%rsp'
apply-hack.x86-64.S:37: Error: unrecognized opcode `movq %rdi,%r11'
apply-hack.x86-64.S:38: Error: unrecognized opcode `movq %rsi,%r10'
apply-hack.x86-64.S:39: Error: unrecognized opcode `cmpl $6,%edx'
apply-hack.x86-64.S:40: Error: unrecognized opcode `ja l2'
apply-hack.x86-64.S:41: Error: unrecognized opcode `je l3'
apply-hack.x86-64.S:42: Error: unrecognized opcode `movq $6,%rbx'
apply-hack.x86-64.S:43: Error: unrecognized opcode `subq %rdx,%rbx'
apply-hack.x86-64.S:44: Error: unrecognized opcode `shlq $2,%rbx'
apply-hack.x86-64.S:45: Error: unrecognized opcode `lea l3(%rip),%rdx'
apply-hack.x86-64.S:46: Error: unrecognized opcode `addq %rdx,%rbx'
apply-hack.x86-64.S:47: Error: unrecognized opcode `jmp *%rbx'
apply-hack.x86-64.S:48: Error: unrecognized opcode `lea 48(%r10),%rsp'
apply-hack.x86-64.S:49: Error: unrecognized opcode `movq 40(%r10),%r9'
apply-hack.x86-64.S:50: Error: unrecognized opcode `movq 32(%r10),%r8'
apply-hack.x86-64.S:51: Error: unrecognized opcode `movq 24(%r10),%rcx'
apply-hack.x86-64.S:52: Error: unrecognized opcode `movq 16(%r10),%rdx'
apply-hack.x86-64.S:53: Error: unrecognized opcode `movq 8(%r10),%rsi'
apply-hack.x86-64.S:54: Error: unrecognized opcode `movq (%r10),%rdi'
apply-hack.x86-64.S:55: Error: unrecognized opcode `xorq %rax,%rax'
apply-hack.x86-64.S:56: Error: unrecognized opcode `call *%r11'
make[1]: *** [apply-hack.x86-64.o] Error 1
make[1]: Leaving directory `/home/ifilgueiras/sources/chicken-4.8.0.1'
make: *** [all] Error 2
Well, it makes sense, since this configuration is trying to use some x86 assembly in MIPS stuff. :)
Any ideas?