What are the procedures to get a revoked mechanics certificate reinstated?
I think you've to apply for a certificate again after the required period and take the tests again. From 14 CFR §65.11 Application and issue:

(d) Unless the order of revocation provides otherwise—
(2) A person whose mechanic or repairman certificate is revoked may not apply for either of those kinds of certificates for 1 year after the date of revocation.

In your case, you have to wait for 1 year after the final conviction to apply. From 14 CFR §65.12 Offenses involving alcohol or drugs:

(a) A conviction for the violation of any Federal or state statute relating to the growing, processing, manufacture, sale, disposition, possession, transportation, or importation of narcotic drugs, marihuana, or depressant or stimulant drugs or substances is grounds for—
(1) Denial of an application for any certificate or rating issued under this part for a period of up to 1 year after the date of final conviction;