No. T42 = 9,5mm (anti)standard. Nec 6650 = 12mm standard, wont fit inside T4X series without using good hammer. You got only 3 choices according to thinkpads.com forum:
"T40p-41p use UJ-812B, its DVD-Burner, write 2X DVD-R/RW/RAM and 16X CD-R.
T42-43p some type use UJ-822S, its super multi, can write 2.4X DVD+R/RW, 2X DVD-R/RW/RAM and 24X CD-R.
now, T43 had new super Multi, UJ-832S, can write 4X DVDÂ±R, may support DVD+R DL."
However those with older thinkpads (like myself, got T23) can use Nec 6650. You need IDE adapter stuff from your old T23 CD player (3 peaces) and you need to cut the rectangular 'hole' at release mechanism. Done in 2 minutes. I repeat, T4X series=out of luck (won't fit inside). Hope this helps.
Pardon my French.