What Treatments Are Available for Hyperhidrosis of the Scalp?

Botox is an excellent option for sweating of the scalp.  It can provide anywhere from 3-6 months of relief depending on dosage.  It would involve a series of small injections.  The surface area of the sweaty scalp will determine how much you use, but a safe starting dose would be 50 units.

Sweating is not a bad thing and on a hot day helps to serve to cool you down.  If this only occurs with exercise, you should see if a simple solution such as a headband can help control sweating.  

If the sweating occurs outside a normal context of exercise, other options include the use of antiperspirants (not great on scalp or for hair though) or botox.  
Craniofacial hyperhidrosis typically involves several treatment options:
Botox- The standard for hyperhidrosis with local side effects only.  May require a larger dose for the scalp.
Oral medications- Typically involve anticholinergic medications such as glycopyrrolate and are not well tolerated.
Topical medications- Usually not advisable to put drysol on the scalp
Surgery- May be last resort for some patients but hyperhidrosis treatments tend to be moving away from this
LASERS/Miradry/ Radiofrequency- Very effective in other parts of the body.  Not ideal for scalp as some hair loss can be seen.

since your problem seems related to getting too hot, it's really not a medical disease but just an overactive response to increased body temperature...the way your body cools itself...evaporative cooling...since it seems to bother you, you're a candidate for botox...in this area topical agents are messy and ineffective and oral products have too many side effects and generally don't even work...botox injections placed superficially into the skin generally will alleviate the problem for about 6-12 months after a single session...sounds like a perfect solution to an uncomfortable problem...