Perhaps what I'll say is stupid because I don't know ITSM 7.0, but is there Data Management Tool in 7.0?
I know that on 7.6.04 there is an excel file with which you can insert "old" incidents.
It's file "transactional-incident".
Perhaps you could use it anyway to see which are the mandatory data? But indeed "IncidentID" is one of those mandatory data.
Perhaps instead of injecting in HPD:Help Desk you should try "HPD:IncidentInterface_Create"?
In 7.6.04 sp2 "Contact Company" in form HPD:Help Desk has a label "Company*+" and has ID 100....082.
I will suggest to use SOAP UI tool to emulate a regression test case. We can do regression and load testing with this tool for free of cost.
All you need is to build the webservice for that respective form and consume through SOAP UI.
This SOAP UI tool can generate test cases. You can specify 100, 200, 1000 dependes on your need for the number fo records to be created at remedy.