On my x86 system with APIC enabled the kernel tells me on bootup:

---------------------------------------------------------------------
Search for ACPI INTSRC's
ACPI header found for Interrupt source override: bus:0, SrcIRQ:0, GSI:2, Flags:00000000
** NEED A RESOLVER for ACPI INTSRC FLAGS **
[0] IOAPIC 1 intsrc: busid:0, busintr:0, gsi:2, flags:00000000
Overriding pin 2 intsrc @ idx 2
checking GPIO pin 2 .. no
checking GPIO pin 3 .. no
checking GPIO pin 4 .. no
checking GPIO pin 5 .. no
Clearing 24 IOAPIC entries
Configuring 24 IOAPIC entries
[0] vec: 54,   cpumask:00000001, ID: 1, busid:0, busintr:0, dest intin:0, type:3, flags:00000005
[1] vec: 55,   cpumask:00000001, ID: 1, busid:0, busintr:1, dest intin:1, type:0, flags:00000005
...
[23] vec: 77,   cpumask:00000001, ID: 1, busid:0, busintr:0, dest intin:23, type:0, flags:0000000f
IOAPIC 1: successfully configured 24 vectors from 0 to 23
MSI interrupt = 0x00000100
MSI vector no = 78 0x0000004e
MSI vec count = 177
---------------------------------------------------------------------

How can I change priorities? 
For example I want Interrupt 11 (got from the HPET chip in x86 systems) at the highest priority less than vector 54.

Must I write direct into APIC registers?
How can I move an entry in the IDT to another place?
This need not to by dynamic at runtime. It's enough to set the prioritys static on bootup

Thanks

Gunther