You might want to freshen up on how boilers work a little bit
As LastElf stated above (but I'll expand on), a feature that's been Railcraft for quite some time is the fact that soild fuel boilers will restock themselves from adujacent inventories. That means, your buffer chest with redpower timer might as well be sitting right next to the boiler with no redpower stuff at all.
You know what else can sit right next to the boiler? A ME interface. Tell it to keep 1 charcoal exported, and the boiler will see the chaorcoal and grab it.
Then, make sure your ME network knows a crafting pattern for 1 charcoal.
What will happen is that the ME interface will try to export 1 charcoal, but fails because there is none available. This triggers an autocraft request for 1 charcoal, using the pattern provided (for example, it could insert 1 log into a furnace). The system waits until the furnace is done processing, imports the charcoal back into the network and uses it to fulfill the ME interface's request for 1 charcoal. Voila, the interface now has 1 charcoal exported... which the boiler immediately steals for itself. The ME interface will be left without charcoal again, and it will go trigger another autocrafting request.
This will repeat until the boiler's four internal slots are all filled with 64 charcoal each. Then, it will no longer take the charcoal out of the ME interface, which is thereby satisfied and stops requesting more charcoal to be crafted. Until, of course, the boiler finishes consuming another unit and restocks itself.