* install extensions: gtk2-dev openssl-dev compiletc squashfs-tools libtool-dev gpgme-dev
* export CFLAGS="-mtune=generic -Os -pipe" CXXFLAGS="-mtune=generic -Os -pipe" LDFLAGS="-Wl,-O1"
* ./configure --prefix=/usr/local
* make
* make DESTDIR=/tmp/sylpheed install-strip

* split into sylpheed.tcz, sylpheed-doc.tcz, sylpheed-dev.tcz, sylpheed-locale.tcz based on files included in earlier extensions.
 - mkdir -p ~/src/sylpheed_ext/3.7.0,2/sylpheed
 - cd ~/src/sylpheed_ext/3.7.0,2/sylpheed
 - for dir in `sed 's/\/[^/]*$//g' ../../3.7.0/sylpheed.tcz.list | uniq`; do sudo mkdir -p "${dir#/}"; done
 - for file in `cat ../../3.7.0/sylpheed.tcz.list`; do sudo mv /tmp/sylpheed/"${file#/}" "${file#/}"; done
 - Note files not found.
 -- Repeat for sylpheed-doc
 - tree -ap /tmp/sylpheed
 - move remailing files to appropriate locations (files not found earlier are a hint)
 - cd /tmp/sylpheed
 -find -type f
  - Finds any files missed.
 - cd .. 
 - sudo rm -R sylpheed
 - cd ~/src/sylpheed_ext/3.7.0,2/
 - sudo chown -R root:root *

* Generate file lists:
  for dir in `find -maxdepth 1 -mindepth 1 -type d`; do cd $dir; find usr ! -type d | sed "s/^/\//g" > ../$dir.tcz.list; cd ..; done
* Generate extensions and checksums:
* for dir in `find -maxdepth 1 -mindepth 1 -type d`; do mksquashfs $dir ${dir#./}.tcz; md5sum ${dir#./}.tcz > ${dir#./}.tcz.md5.txt; done

* tce-load -i sylpheed
* sylpheed &

Works!

* Tested after deleting all links in /usr/local, added font, curl, and iconv dependencies.