I have used both Timbor and Boracare - I have mixed both myself since in Europe they are not available.
I was much happier with Boracare for the reason that it penetrates the wood deeper and faster than Timbor, and because the finish is better. Without glycol after some months you will have the tiny salt crystals resurface on the wood, and they are visible under the clear topcoat. Not that nice.
You can make your own borate soution following the instructions at this link.
Chemotherapy for Rot
It will be MUCH cheaper than buying the stuff.
If you use ethilene for a glycol do not breath the fumes as you boil the mixture.
I DO NOT recommend using antifreeze for glycols. Antifreeze contains antioxidants that will retard the absorption of the mixture and take MANY days to dry.
If you work with chemicals you can get pure Ethilene Glycol or Polietilene Glycol or Propilene Glycol for cheap.
I do not work in chemicals but still have no problems buying the stuff in 1 gallon pails, at the same chemical wholesaler where I buy the Borax and Boric Acid.
Ethilene glycol is not that bad as you will read on the internet UNLESS YOU EAT IT OR DRINK IT. The other two - Propilene and Polietilene - they are used also in the food industry, so they are safe. However since ethilene is a boicide it will add to the borates to control the pests, be it insects or molds and mildews.
So if you don't have problems with pets or kids gnawing at your cants ethilene is the more effective glycol to use on INFESTED wood. But for prevention it is not really needed, so just be on the safe side and go with one of the other two.
I always spray the logs or cants (or whatever wood has to be stocked for long periods) with Boracare.
Boracare is just as good (or possibly even better) sprayed on green wood, because borates love water and therefore will spread into the wood faster and more evenly when the wood has high moisture content. Wetting dry wood before applying boracare is not recommended.
Any wood treated with borates will either have to be stored in a dry place or coated with a film forming finish to prevent borates from being washed away by the rain.
As to pyrethroids. They are very effective at killing the pests, but they are more dangerous to mammals (lethal to cats), so I would not recommend the use of phiretroids unless you are in need to remove the pest more than preventing reinfestation. Also phyretroids are not as good as borates at preventing reinfestation.
I have once added permethrin to an ETHILENE glycol borate solution to treat a log staircase that was BADLY infested with wood borers. That mixture did an EXCELLENT job.
So it can be done and it works, but it's not what you need unless you have a really bad case.