I've managed to build CLISP (with FFI support) on N900. It was very torturous experience involving learning ARM assembly, working around GCC miscompilations and unexpected optimizations, fighting bugs like accidental endianness switch, malloc+mprotect problems and so on, and so on. As far as I understand, CLISP's ARM support was done for RISC OS and it depends on its 26-bit calling convention (APCS-26). It worked on N8x0 by pure accident, and with newer kernel / libc on Fremantle it all went haywire. As of now, I have working CLISP, ASDF, SLIME. Most important libaries seem to work. I'm currently trying to get cl-gtk2 to work (as of now, it segfaults) to see whether ffcall still has any serious problems and to make a nice GUI demo. I'll prepare and distribute all necessary patches soon, but if you're in hurry, you can get my preliminary patch against clisp-2.48 here (didn't make the ffcall patch yet). BTW, there's little hope to get CLISP to run under qemu. You're better off using it on the device or under x86 scratchbox, where you can also use SBCL to have more comfortable development environment, if your code is portable enough. CLISP can be used later for deployment on the device.

Edit: don't waste your time even trying to build clisp under ARM scratchbox. Build it on the device with the patch linked from this message. You'll need to add SDK repository and free up some space in the root partition to be able to install gcc, binutils etc.
I repartitioned my device and moved /usr to eMMC in order to achieve this. There are also other approaches, see wiki.