Is it possible to speed up block chain syncing with a miner?
Syncing means:


Downloading the blockchain.
For every transaction, check that its inputs actually reference earlier unspent outputs, and that the signatures match.


Hashing is a completely negligible part of the process and a mining device will not help you. Computationally the major work is verifying ECDSA signatures, and you also need disk access to find the past outputs. Using an SSD will make things faster.