Arbitrary amount of BETWEENs

Hi...

I have an index organized table on which i'll be carrying out a select
of the following type...

select value from table
where key between 1 and 4 or key between 9 and 11 ....... or key
between 100 and 201

The current issue is, that the amount of range selects is arbitrary
and in worst case this query could end up awfully long. All that comes
to my mind right now is gluing a string up dynamically in pl/sql and
executing it... However.. Makes my stomach turn over big time as I'm
guessing this involves serious parsing and processing overhead
eliminating the win-win on doing range selects on an index organized
table...

I'd appreciate if anyone could point me in the direction of a cleaner
approach which i might have overlooked :)

Regards :)
.