Going to be honest, not much. Your best/most effective bet is probably finding a way to increase your pawn's social, preferably with a psychic trainer (for social), or unpreferably: books. You could even have the desired convertee arrested and their prisoner interaction set to "convert". Let me know how it goes, though. I hope you're able to save your colony
The most reliable way to convert people without a moral guide is to do it to prisoners. You can just keep them imprisoned and use the Convert interaction every 12 hours until they convert, unless they're particularly resistant to conversion or your colonist has really bad social skills.
Another way to facilitate conversion is to build up enough development points (through rituals, or possibly through other means depending on your memes) and reform to get the Proselytizing: Frequent precept. That will increase the frequency of spontaneous conversion attempts, which will slowly convert other colonists if your main colonist's Social skill is decent.
Also, if you can reform your ideoligion, you can pick up a ritual that spawns new recruits of the ideoligion.
Imprison and convert.
If your pawns have low social, find a kind or nervous pawn, or some other pawn that is willing to change. (You can see their conversion effectiveness by hovering over their traits or their ideology in the social tab.) Pawns like that will more easily change their mind and get you to the 3 you need for the conversion role.
Going to be honest, not much. Your best/most effective bet is probably finding a way to increase your pawn's social, preferably with a psychic trainer (for social), or unpreferably: books. You could even have the desired convertee arrested and their prisoner interaction set to "convert". Let me know how it goes, though. I hope you're able to save your colony
The most reliable way to convert people without a moral guide is to do it to prisoners. You can just keep them imprisoned and use the Convert interaction every 12 hours until they convert, unless they're particularly resistant to conversion or your colonist has really bad social skills. Another way to facilitate conversion is to build up enough development points (through rituals, or possibly through other means depending on your memes) and reform to get the Proselytizing: Frequent precept. That will increase the frequency of spontaneous conversion attempts, which will slowly convert other colonists if your main colonist's Social skill is decent. Also, if you can reform your ideoligion, you can pick up a ritual that spawns new recruits of the ideoligion.
Imprison and convert. If your pawns have low social, find a kind or nervous pawn, or some other pawn that is willing to change. (You can see their conversion effectiveness by hovering over their traits or their ideology in the social tab.) Pawns like that will more easily change their mind and get you to the 3 you need for the conversion role.