Tim-bor Professional is an insecticide, fungicide and wood preservative for the protection and treatment of lumber against fungal decay and wood-destroying insects. However, is not to be applied to any live trees. Depending on the type of borer being treated, you can look at using a product like Dominion 2L. When using Dominion 2L Termiticide for borers, it is labeled to be applied as a soil injection which includes grid systems, circle systems, basal systems, and soil drench applications.
It is recommended that you use a sealant or paint on the wood treated with Timbor. This will seal the product into the wood so that it will last for the life of the wood. It is not necessary to paint or use a sealant though.
Timbor should only be mixed and applied according to the product label. Because of the formulation, the Timbor solution would most likely clog any type of small applicator you would try to use. Jecta is a ready-to-use borate wood treatment that can be applied to specific areas.