From a more psionic-geared mindset it is possible to evoke with the sole use of energy, but requires mastery of energy manipulation.
I was working with Gabriel last night, and he told me something interesting about the nature of evocation. I asked him if I should make his presence more tangible so he could be more powerful when working with me, he replied:
“Presence is important when evoking, but if you cant make that presence dynamic, it will actually hold the spirit from working.”
Basically, this means that when evoking, we have to balance the spirit’s presence/density of his energy body with the dynamism that will allow such density to be put to use, otherwise we just end with a rock, hard but unable to go anywhere.
If you cant have any tools for evoking rites, you should consider sigil magic. I myself got a great feat from Seere last week, and all I had to do was to open his sigil and strike a deal with him mentally.