to apply dwm and st patches I use the following approach
- copy patches needed to /etc/portage/patches/x11-wm/dwm-6.1/*
- assign numbers to patch files so they can apply in correct order
USE=-savedconfig emerge x11-wm/dwm
- modify /etc/portage/savedconfig/x11-wm/dwm-6.1 (hint: you can symling dwm-6.1 to dwm-6.1.h to get syntax highlighting in vim)
- enable savedconfig USEflag for dwm
flaggie dwm +savedconfigi
- emerge dwm
- repeat for x11-terms/st