If you have a /dev/dm device, you HAVE presented the LUN. This is the multipath daemon's way of abstracting the multiple paths as one device.
That way, assuming you had /dev/sdb, sdc, sdd, sde as 4 paths to the same disk, you would use /dev/dm-0 as the path you choose, and if you lose /dev/sdc then you still have 3 active paths and no loss in access, but perhaps performance
(Besides, an EVA only allows access via one controller at a time until a failure causes it to switch controllers. It's really the "Speak and Spell" of SAN technology)
In the Command View EVA tool you present the device to the WWN(s) of the host (You did properly zone the switch, correct?)
After that, you should follow the instructions on this page:
Scan and Configure New LUNS on Redhat Linux (RHEL)
If you are using native multipathing, run multipath -ll
Make sure the system sees all the paths. You can also create a disk lable with e2label (That way, when you run blkid, you can see which devices correspond to which path, etc without multipath -ll)
Tutorial: e2label, fdisk, /etc/fstab, mount, linux rescue, rescue disk, CentOS should help you there.