You would have to figure what wires on the fan do what (+/-), and then attach a servo connector to it. The thing that I would be concerned about is the fan doing damage if it came off, being as it's a spare I doubt you care about the fan but I don't see it lasting too long attached to a MT that gets bashed. If the fan kicks it, do the remote start.
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How do you plan to attach it to the engine? Attaching it to the head may put too much stress on the cooling head bolts. Just something I thought about but I'm not too sure, I don't know what the fan weighs.