Yet another post regarding my friends office!

Even making use of port economisers, I am going to have to run some
CAT5 cables including 2 or 3 cables across a ceiling.

Unfortunately, I am fresh out of skyhooks and the suspended ceiling
that is in place appears to use some kind of interlocking type tile and
I am not keen to take any of these down in case I can't get them back
up! Does anyone have any suggestions as to how this system works?

The alternative is to fix some mini trunking to a structural beam, I
can't drill and plug this even if I wanted to as the landlord would get
upset. Also it would involve a lot of extra work putting down dust
sheets and clearing up aftewards and I think the job will be long
enough anyway.

If I have to go down this route, I will use trunking thats approx 1"
wide by 1/2" deep. If I use a good quality Self adhesive type, how
long might this be expected to stay up (18' span, trunking mounted on
front face of a concrete beam covered in well stuck matt paint.)
minutes, or years?

Alternatively, How practical is it to use plain trunking and fix this
with impact adhesive?

Any other suggestions?