Tvheadend

Okay, so maybe I'm being a bit thick, but for the life of me I can't seem to achieve what I want in TVheadend....

All cards, multiplexes, services, and channels are all fine and stored, and EPG is working for the most part.

I can select items from EPG and set these up for recording, on both schedule and autorec, and this all works fine.

However, I want to record a channel for a duration and have nothing to do with EPG.
So lets say I want to record BBC 1 from 09:00 to 17:00 every day. How can I achieve that in TVheadend?
Of course I could add it manually, every day. But the point is that I want to set and forget a schedule.

Seems so simple, yet I've spent a chunk of time today trying to achieve this.
It looks like I could probably achieve this via editing the files created in ~/.hts/tvheadend/autorec to add in a duration - but can't determine if there's a defined command for that...

Also, if I wanted to record multiple channels from the same transponder, also by duration not EPG, I assume once it's possible to do this once, it's possible for multiple channels?

I've looked into options around just mplayer, szap or dvbstream, but difficult to get multiple channels without doing entire TS dump which I'd prefer not to do.

Anyone with any ideas on how to achieve this (simple) task?

Thanks in advance
Dirk