Create bucket type with the table_def
property.
export TAB=GeoCheckin; dev/dev1/bin/riak-admin bucket-type create $TAB "{\"props\":{ \"table_def\": \"CREATE TABLE GeoCheckin (geohash varchar not null, user varchar not null, time timestamp not null, weather varchar not null, temperature varchar, PRIMARY KEY((quantum(time, 15, s)), time, user))\"}}"
Activate it:
dev/dev1/bin/riak-admin bucket-type activate $TAB