Yonten Jamyang,
We need to get rid of this idea that only 'highly qualified monks can perform such offerings'. Any practitioner whether lay or ordained, male or female, who gathers the appropriate conditions can perform fire pujas. Perhaps the way you wrote that did not have the meaning I interpret, but there is definitely a cultural holier-than-thou perception passed around that is not in touch with the reality of the situation, which is that you do not have to be ordained with a high rank or tons of traditional ritual knowledge to be a qualified practitioner who has accessed the lineage blessings.
From what I've read, in order to perform the burning offerings of Dorje Shugden, it is usually required that the practitioner receive life entrustment, Vajrabhairava initiation, and complete a Vajrabhairava close retreat including the subsequent fire puja. I can't remember if it was also required to complete a Migtsema close retreat and a Dorje Shugden close retreat as well, but hey, I'm sure you couldn't go wrong adding those to the list. Though these requirements were mentioned in the transcript I read, it is probably best to ask our Lama what is required, then make offerings and request instruction and to receive blessing that we may gather the conditions to complete these things, so that we may destroy samsara at the root.