For what it's worth, I just took a 1.6.2ish (not quite) system to
-current (sources from mid february).  The build (with build.sh) went
fine, and I tried to do the install after placing the current kernel
in / but before booting it.  The base set installed, and then I got
bad syscall errors on the rest.  So I rebooted into the 1.6ZI kernel
(which I know the instructions say; I'm used to 1.6->1.6 upgrades
where you can get away with this) and did the install again, and all
seems ok.

-- 
        Greg Troxel <gdt@ir.bbn.com>