The bits/bytes problem in NagVis is a little bit more difficult.
It is not possible without a small code change.
The old thread was also with @BH2005 
Google translate should also work for my German in that post
The match string inside NagVis looks like this
'In: [0-9].*bit/s.*Out: [0-9]+'
But the output in CMK is this
In: 77.9 kBit/s (<0.01%), Out: 11.6 kBit/s (<0.01%)
This will not match.
My solution from the old post is a general solution for all interface to show the traffic in bits.