The following command turns on ascending insert mode for the sales table:
dbcc tune (ascinserts, 1, "sales")
To turn ascending insert mode off, use:
dbcc tune (ascinserts, 0, "sales")
These commands update the status2 bit of sysindexes.
If tables sometimes experience random inserts and have more ordered inserts during batch jobs, it is better to enable dbcc tune (ascinserts) only for the period during which the batch job runs.