I've merged the patch from Anton Kovalenko to use TLS slot 63. There was some minor hiccup - I merged one commit but totally missed the next commit in the series and lost some trying to untie the know.
I've then reabased my branch onto SBCL-1.0.45 and published the binary to https://sites.google.com/site/dmitryvksite/sbcl-distr/sbcl-1.0.45-threads.msi.