why not just run a script something like this:

while true
do
sleep 24 hrs
if charging
then
updatedb
done

I usually leave my n810 plugged in over night,
so if I start this script at the right time ....

is there a problem with faking cron like this?

anyway, I'd be happy to run slocate manually so
I hope it gets ported (there is a version for the
770 it seems but it won't install on the n810
see: http://lucidvisions.com/#nes)