In the chär resource, in the onStart field, put K150. That gives you the Nilkemorya rank. Next, you have to figure out where in the mission string you want to begin. Just having the rank doesn't do much but make Polaris ships not attack you. In Resedit/NovaTools, look through the Polaris mission string. When you find the point where you want to start, look at the Availability field. It will contain something on the order of
B100 & !B101
B100 means bit 100 must be set, & !B101 means bit 101 must not be set. In your chär's on start, put B100. Look at the rest of the availability requirements- such as ship type and whatnot. Make sure your chär is set up to provide this.
Last, the hard part. You may want to get ahold of the Nova Bit Bible. You need to backtrack through the missions from your starting point, and make sure all the bits they set are set in your onStart field. It's like a context switch in an OS, really. Nova must not realize that these missions where not actually completed- the enviroment must be indestinguishable from having actually done the missions.
Get the EV:N bible, and read it. Read it again. Do this first.
Good luck, hope you realize what you are getting into.
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~Charlie