I'm not sure if it'll work in DOS 6.22 and earlier CONFIG.SYS, but you can use PAUSE after every few commands in CONFIG.SYS and AUTOEXEC.BAT or you can tap F8 to get the Safe Mode Menu in DOS 7 and select the Line by Line Verify option. Then you can go through and check each step.
Another way is to use a command like:
echo > c:\startlog.txt
to make DOS port the startup text to the file c:\startlog.txt, then use a text viewer to review the events.