load the log into a temp table then do a query against the date column

create table @errorlog (date, source, message)

insert into @errorlog exec sp_readerrorlog

select * from @errorlog where date >= '' and date <= ''

there is no way to pass in a paramater to the sp_readerrorlog that I know of, other than using the log viewer but that will read the log then filter it down which is the same as the above.