FreeSwan is available in gentoo-sources and there is no freeswan in -test-sources. Please add :).
I'll see what I can do...
I would recommend to change that patching ... freeswan supports "make module" and "make minstall" to install ipsec.o into /lib/modules/.../ IMHO it is much less work to add these two make-Commands (or just "make module minstall") into the ebuild of freeswan... I am running gentoo-test-sources-2.4.22 and did it by hand
done