There's a thread on the forums from someone who hex-edited the drivers in Nero 184.108.40.206, changing the ID string for the NEC ND-2100A (the DVD+ only version of the 2500A sold to OEMs such as Dell) to that of the ND-2500A. Only then was he able to use his ND-2500A in Nero 5.5.
You can read that thread here.
There's no official support for the ND-2500A in Nero 5.5 - there probably never will be, as it looks like Ahead have pretty much dropped all support for Nero 5.5 now. The only way to get official support is to upgrade to 6.0. If you try the hex editing trick, it's very much at your own risk.