How to schedule a one-shot job without crontab on openwrt?

Is there a pre-compiled version of the at/atr/atrm on any stable releases of openwrt or I must build it from scratch?
I know the cron/crontab command, but I need execute some actions at specific time instead of periodicly. If I use cron, I have to clean up the crontab after the action has been executed.