Most likely it supports DL burning.
Open Temrinal.app.. type:
drutil info
And see what you get as supported DVD writes.
yellow% drutil info
Vendor Product Rev
PIONEER DVD-RW DVR-109 1.17
Interconnect: ATAPI
SupportLevel: Apple Shipping
Cache: 2000k
CD-Write: -R, -RW, BUFE, CDText, Test, IndexPts, ISRC
DVD-Write: -R, -R DL, -RW, +R, +R DL, +RW, BUFE, Test
Strategies: CD-TAO, CD-SAO, CD-Raw, DVD-DAO
As for firmware, I don't think so. AFAIK, it's a hardware limitation.
Unsolved 
