You could use dual parabaloids, or a texture atlas. I achieved both without modifying Irrlicht. (And I didn't use any of that exposed video data junk either.)
Theres an article on GameDev.net about dual parabaloids, check it out.
Cubemapping
ShadowMapping for Irrlicht!: Get it here
Need help? Come on the IRC!: #irrlicht on irc://irc.freenode.net
Need help? Come on the IRC!: #irrlicht on irc://irc.freenode.net