Try this :
when you see the lilo choice screen (with the Mitel logo), press the TAB key to enter the command line mode of lilo. Then you can type :
Mitel-SME-up single
to start in runlevel 1 (maintenance mode of linux : no network, no multiusers).
You'll have a root shell where you can fsck all but 'root' filesystems
I haven't done on SME but it works on a Redhat, so should work on SME.