The MMC specs doesn't really go into detail on addresses for which -268435455 (F0000000h) to -45151 (FFFF4FA1h) represents. But in my tests, it seems that F0000000h is a constant to represent the starting ATIP address, which is different on each CDR manufacturer. If you keep increasing, you will endup reading the first pregap and some track 1 data, before you reach the max -45151 (FFFF4FA1h). Going further, i.e. -45150 (FFFF4FA2h) will be in another range, which is not in lead-in because it's 90:00:00 (m:s:f) as in the above table and they want that to mean the outer edge of cd.
Procedure to read sector in lead-in (try with your Plextor):
In "View Sector" turn on raw subchannel reading option, then and in the sector viewer, enter $F0000000, then $F0000001, increasing, etc, or just press ">" button.
It should give you funny looking sectors mostly 0s. If you look at the subs (turn on deinterleave subch data), the first 8 bytes are Ps, so should be all 0, next sets of eight bytes are Qs, it should be a recognisable TOC entry. You'll notice that the TOC entries will repeat 3 times each. Normally the sectors are encoded as CDDA, but, sometimes on data discs the sectors are in CDROM format and you'll see the sync header at the top.
If you go into "View TOC" select "Full TOC info", which should give you interpreted Q raw TOC info. If you select "Display in raw Q format", you'll notice that these are the Q subchannel data and these can be compared to the ones you get in "View Sector".