Database Software

Firstly, I'm aware that the following is not the recommend solution, just looking for feasability.

customer has a 2 node rac, on aix 5, using asm, 2 disk groups, data and flash. we have 5 instances running on these 2 disk groups. customer has taken an image copy of the disk that contains only the flash disk group, copied to new disk. Using another machine, installed the same oracle software, set up asm, mounted the disk, asmcmd is working, i see the backup information, i don't see the spfile directly, autobackup was not used for spfile, so i don't see it, although they are performing full backups, i'm assuming that somehow, it must be there. customer wants to use part of this disk for recovery, by removing 4 of the 5 instances, to make room for a recovery, basically, they want to test this scenario on only one instance. they want to mae a directory under the flash disk group for this one recovery. i'm imagine that we need yo use setnewname.
Please give some advice on how to go about getting this spfile, and restoring this file to another area of flash, and then the same for control files, db.

thx
rob