I've just finished uploading pre-built images for the 11.10 release to:
http://releases.linaro.org/images/11.10/oneiric/
These are built with default options from Linaro Media Create to pre-set sizes. You can install these with 4 simple commands:
$ SDCARD=/dev/sdb $ IMGFILE=overo-nano.img $ gunzip ${IMGFILE}.gz $ dd bs=4k if=${IMGFILE} of=${SDCARD}
-andy