go around the command
select the desired buses and then create a bundle with the selected
ex
select class add*
; use wild card to select multiple objects P0_addXX and P1_addXX can be selected by using p?_add*
define (bundle bundle1 (nets (selected)) (gap 15 (layer INT1_LAYER4 INT2_LAYER5 INT3_LAYER8 )))
but a word of advice, this won't give you a desired result, because you over strain the auto-router.
an achievable approach will be like this
1. determine the critical buses and decide their flow ex. a pci bus may go from u1 on top right to u30 on bottom right
2. with a help of excel sheet, allocate routing layers in alternate fashion for different buses. make sure that you don't cross the path
ex for a 16 layer brd with 6 internal layers
Bus layers direction
pci int1, int6 H,V
add int2, int5 V,H
3. now take one bus at a time, define a fence such that the desired bus dont stray all over the board
4. make sure that you limit vias and have a via free zone where you expect criss-cross (define the via grid to 25-50mils)
5. route, mitter, and protect the routes after you get the desired result.
this way you save a lot of time and the routing will be more manual like, in the sense, you will spend less time in correcting DRC's after auto-route.
for a start take a test board and practice auto-routing. once you get the hang of it, you will become an expert
best of luck
regards