I would recommend BIWS for someone without direct experience that has an Excel modelling test in a week.
If you're trying to generally get better at your Excel / modelling skills then I'd recommend this book off Amazon:
https://www.amazon.com/Modeling-Structured-Finance-Flows-Microsoft%C3%82-Excel/dp/0470042907
I trade ABS bond at a fund and I used to spend time for modeling at sell at buy side as well. I would say that fresh out of school there is big potential there. It is true, structured products require some numbers crunching, but it is nothing similar to rocket scientist. One book I would mention is the step by step guide: https://www.amazon.com/Modeling-Structured-Finance-Flows-Microsoft-Excel/dp/0470042907. that definitely is enough to get you equipped with the numbers technique. also Fabozzi's fixed income book (just 2-3 chapters) can get you some solid background for the whole sector.
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Dont think you need to worry about fancy models at this moment; the hiring manager wont expect you know those. just simple amortization model, prepay, default concept, and asset/liability, and leverage solid understanding. Those should be enough.
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Good luck