I used to carry mine utilizing the pump nub on the HT. It rattled and one time actually fell off while riding.
I only have two with Campy heads. They are different sizes with only one really fitting the larger frames. The smaller one was purchased back in the '70s so it has spent its life with me.
They both work, just not well enough to take the pressure to 120. It can be done but like other said, it is dependent on the technique. Wrap your index finger around the head, have the valve pointed down or have the wheel "hanging" from the pump head, then pump. Getting to 100psi is tolerable but the rest is too much for my old arms.
Both are in a storage bin now.
Pump 1 on 59 ST
P1050284 on Flickr
Pump 2 on 56.5 ST
B_Y_DS on Flickr