Thank you. I love manuals and did read mine.  I must be missing it.  Can you point me to the correct page?

I'm not in front of my TV, but here is the general idea, until you get the real directions from the manual:

The "Connections" menu is where you want to work.  There is one level of indirection, so each "Device" gets to say which video connector and (in some cases) which audio connector it comes from.  What I would do in your case, if you're giving up on cable television, is re-assign the "TV" Device to use "HDMI A", and crane your neck around underneath the BV10 to see which of the 3 connectors that is.  Might as well take the audio from the HDMI too, unless there's some reason the Roku device won't do that.  You don't say which remote you're using, so I can't give you keypresses.  But I used an old BeoRemote 1000 and its "Menu" button...  Truly it's simple, and you'll be making it so the "TV" button on your remote will turn the BV10 on and select the correct input connector.

 (One tricky bit for me was that the arrow keys were counter-intuitive, and the "Play" button stored my selections.  The other tricky bit was it would not assign the HDMI port to a new device until it was released (unused) by another device.  Thus you might choose to plug the Chromecast in to exactly the same HDMI port the cable box output was (assuming it was a HDMI cable box and not a DVB tuner).)

Look for:

Register additional video equipment

In the pre Aug 2010 english version it is on page 12.

https://www.bang-olufsen.com/~/mediaV3/Files/user-guides/beovision10/beovision10_guide_english.pdf

Ralf

Ralf-thank you for taking the time to send me the link.  I will try it tonight.  Carla

Thank you for this information.  I'm going to give it a whirl tonight!  Carla:)

HI!  Your instructions worked!  Thank you for the tip about unplugging cable connected to HMDI.  I returned my cable box this morning  and Roku is working!  One more question-do you know how to program the Roku remote, so I just have one remote?  I got stuck during that phase of programming.  Thank you.  Carla!

Hopefully someone else will chime in, because I have no experience with the Roku.  Their support claims you cannot train the Roku remote to drive a B&O TV.  Vice versa, if you have a local B&O dealer, ask them if there is a PUC for that older TV to drive *any* model of Roku stick, so you can use a Beo6 or Beo4 remote?  

For my TiVo and BeoVision 10-46, I bought a Logitech Harmony Hub and used their iPod Touch app to drive both devices.  It worked as advertised, but I hated its illogical and multi-page-swipe button arrangement.  I could have added their hard-button Harmony remote, but I decided simply to use a BeoLink 1000 to turn on the TV and do volume, then grab my (RF) TiVo remote to control the tuner/recorder.  Yes, it feels kinda 1980's to have multiple remotes, but each was carefully customized for its purpose.