At this time, I think you are stuck as I've been scripting the partition creation. To my knowledge, there is no auto-generation of partitions. See
http://forums.mysql.com/read.php?106,52423,52423#msg-52423
I suggested this as a feature a while back and I think it's still one of those things that will be fun for the team to try, but will require a reasonable amount of work to implement (the suggestion used a year as an example, but would extend to any logical time period - I really want days and a followup post by another individual clarified the community's desire for that functionality).
Mikael responded that it is on their "Idea list", but would take a bit to work out (there's no easy way to get there from here)... In essence, they will probably need to rewrite the "Out of Range" error handler to do math and figure out what the next partition should be based upon the create statement, then throw an alter table and retry the insert... all on the fly. There's a better explanation of the existing behavior at
http://dev.mysql.com/doc/refman/5.1/en/partitioning.html in the section on range partitioning, but the solution provided there involves creating a "catchall" partition, and juggling the data later.