Hibernation does with with Boot Manager installed.  The key is to make
the FIRST primary partition FAT16 sized to at least the installed
memory plus 35 MB.  If you plan to upgrade memory size in the future,
make the partition that much larger.
Install Boot Manger into the SECOND primary partition. (In fact Boot
Manger can be anywhere on the disk, except for the first partition in
this case, as long as it is within the BIOS 1024 cylinder limit) The warnings about OS/2 & Boot Manager were probably written by M$
trained programmer with tunnel vision.

I have been hibernating my TP T41 for over two years now.  Disk setup:

No.  Type       Size         Format    Letter     OS
1.      Primary  657 MB   FAT16     C:
2.      Primary       7 MB   Boot Manager
3.      Logical   512 MB   HPFS      D:           eCS 1.1
4.      Logical       2 GB    HPFS      E:            eCS 1.2.1
5.      Logical       2 GB    JFS          F:
6.      Logical     30 GB    JFS         G:


Cheers,

Chris