David Fojt,
To my understanding this was the Rossi way in the photos posted in these pages by Alan Smith (year 2008):
1. Put catalyst powders in a closed tube.
2. Apply variably changing temperatures within a 150-500°C range.
3. Inject hydrogen impulsively at a variable rate and a target pressure in the 2-20 bar range.
At the temperatures of these prototypes I don't think that sintering was a too big issue yet (except for hot spots) and agitation of the powder may also have serendipitously occurred during each hydrogen injection pulse, with possibly positive effects on the reaction (for example static charging?).
I do not think that advanced power control was used at the time if not for changing temperatures variably up-down to drive hydrogen off from the lattice to the nanopores. Rossi claims in a recent provisional patent application that the heat can also come from with external chemical heating, so for the anomalous effect itself it must be not necessary to have complex AC power. However it is possible that this effect may have been used in Lugano (as you hypothesized) to induce agitation or movement of the powder that was done in different ways in simpler prototypes.
☞ I must note that all the early prototypes of Rossi were submerged in water and this may or may have not been important. A jacket for the absorption of radiations was an important part of his patent application.
As for Holmlid from what I read around he does not use any special control. Hydrogen is injected through relatively large catalyst pellets, heated with a resistence up to 700°C. Then in his case Rydberg matter and ultra-dense Rydberg matter hydrogen are supposedly produced in the pores and on the surface of the catalysts. From what I understand, after some time anomalous effects start appearing by themselves or it is also possible to shoot a green laser light on the surface of these catalysts to induce them immediately.
Under a very low H2 pressure (used by Holmlid) the potassium alkali promoter of FT catalysts starts sublimating and according to Holmlid their atoms leave the surface of the catalyst in an excited state. This also contributes to the excitation of hydrogen in addition to what already happens in the pores that are on the surface and in the bulk of the catalyst.