Okay I have never heard of a SARM before but I googled it and from what I see I assume it is a steroid that only targets the androgen receptors in specific areas thus trying to eliminate unwanted side effects.. Well first off I wouldn't ever use androgens until I was at least 25 and hit my genetic ceiling. If you cannot hit it naturally, androgens will do little for you because diet/training are wrong. But if you must use it I would refer to the HST ebook for FAQs.
From what I have read, I believe you follow HST as is with a few exceptions:
1.) No Strategic Deconditioning. This is because you do not need to because the androgen is stimulating growth regardless and there is no need to decondition a muscle that is still responding well to the stimulus of resistance training. Once you complete an HST cycle, simply start over but increase your rep maxes a little. (5 pounds maybe 10 for compound movement.)
2.) Skip the 15s. The 15s are used to create an anabolic environment and to repair sore joints and tendons with lactic acid. There is no real use for this. Just stick to 2 weeks of 10s, then 2 weeks of 5s, then 2 weeks of negatives.
3.) Do not increase the amount of weight you do naturally. The androgen will make you stronger. Once you go off you will get weaker because of decreased hormonal levels. If you max out your strength, you will surely lose some of it when you go "off". To combat this, instead of lifting heavier weights than you could naturally, when you are on an androgen, just increase the volume. Do an extra working set if you can and up the reps possibly but keep the load something which you were able to perform naturally.
4.) Do not decondtion until your natural hormonal levels are restored. Nothing will make you smaller faster than going off steroids then deconditioning your body with low hormone levels.
You should follow all other HST protocol as stated on the site. I would just increase volume. Lift 2x a day if you want as long as each muscle group is rested for at least 36 hours before loading once again. Do not think that androgen like a SARM will make you recover faster. An androgen will not decrease the time needed to repair a muscle, it will only increase the magnitude of the stimulus (loading) and create an ultra anabolic environment for the muscle to thrive. Hope this answers your question and please be careful. If you are young you could really hurt yourself which is why anabolics are illegal, people cannot be trusted to use them correctly. It would be wise to do some more research before embarking sir.