for example
alter index myindex on [dbo].MyTable REBUILD PARTITION = 11 WITH (SORT_IN_TEMPDB = ON);
partitioned indexes can't be rebuilt on-line btw.
[font="Comic Sans MS"]The GrumpyOldDBA[/font]
www.grumpyolddba.co.uk
http://sqlblogcasts.com/blogs/grumpyolddba/