If you open Nero without putting media in the drive, you CAN get at the Burn tab and check the box - if it tops out at 32x its either firmware or you need to update Nero.
Nero's support site:
LTR-52246S EIDE/ATAPI 52x24x52x 5.5.9.8 or later
Latest firmware:
http://www.liteonit.com/webfw/LTR-52246S/R526S0C.zip
How to upgrade:
http://www.liteonit.com/english/english-load-how.htm
Also check this (written in finest Chinglish):
Why NERO recording software only allow me to chose 8X or 16X speed after I upgraded to your latest Firmware?
A30
With the Firmware upgrade, your current NERO version may not recognized your drive as high speed recording device. You may solve your problem by doing the following : Start your NERO application
Place blank disc in the drive ( You must use a media certified to support your driveˇ¦s maximum recording speed, i.e. you need a 40x media for your LTR-40125S drive )
In NERO, click on " File ", " Preference ", select " Cache " tab, then select " Test all drive speeds ". Or simply go to disc copy menu, under the " Copy " tap, check the dirveˇ¦s maximum speed. This way, NERO will understand your drivesˇ¦ maximum performance, and allow to choose that speed in the future
( Note : NERO Ver. 5.5.5.6 or later do NOT support writing speed below 8x. If you have chose " High Speed " option during installation, then your choice will only start from 8x. If the above step did NOT solve your problem, then you will need to un-install NERO, remove NERO directly manually from Windows Explorer and reinstall NERO. )