A somewhat convoluted method has occurred to me whereby you could do this, in theory the following steps should work.
1. Find a pre TN race and engage them in a Star Trek style observation period (holo emitters hidden in caves and all that stuff)
2. When the race has reached a sufficient sociological development that they can accept aliens and such, then initiate first contact and begin the process of helping them on their first steps. (drop the ground troops and conquer).
3. Once the race has dealt with the new issues that arise from being a planetary group and is ready to head to the stars, assist them with some knowledge on safe space travel, while staying in contact and fostering close relations for the future.
The last step translates to these steps.
1. Once the race has fully converted to imperial status and all their pre TN facilities have been upgraded then remove anything you want to keep, like all your ground forces and any orbiting hips etc.
2. Create a new NPR race with SM on the same body as the old pre TN race, make sure that the species selected is the same as the pre TN race, set their governemt type etc but make sure you give them zero facilities, population etc etc. Also decide on a suitable amount of RP to give them so that they at least have one or two techs, this can represent the uplifting process.
3. SM full communications and first contact with the new TN NPR and your actual playing empire.
4. Transfer the now colony of the old pre TN race to the new NPR, this gives them all the population and facilities etc to run with, being a full TN NPR from creation they should then be able to progress as per any normally generated NPR and head to space.
If you were to also SM in a set DR with this new race it could help to kickstart the diplomatic process with the new planetary government on the way to good trade relations, just be sure to move your warships out of the system or at least so that only a small sensor boat sits well out of their range to just monitor things.
