I used the experimental stage3 tarball with one of longsleep's Ubuntu images and installed the system from an Ubuntu system running on my Pine (Gentoo card was in a USB cardreader). If you follow the normal steps from the Gentoo installation manual it just works... just leave out the partitioning and kernel / bootloader steps, dont forget to install the kernel modules as well and a sshd... after that I just built some necessary packages to get the platform scripts up and running... I can upload the image once I cleaned it up a little if people want to play with that...
Come have a chat in the Pine IRC channel >>