Travel requests to be entered using iExpenses

Hi,

How can we use iExpenses, for creating Travel requests, wherein the said request needs to be pre-authorized before the same is forwarded to the Travel co-ordinator to proceed with the said booking.

But, while using expense report, the said transaction should follow Purchasing hierarchy and not the iexpenses approval limits.

Or

Is there anyother way we can use the employee self service?

Any help would be very much appreciated.

We are using Version 11i.

Thanks

Srikanth