How to impose Expire Date on MS Office files?

Question

I am using Document Library in MOSS to store MS Office files to make use of IRM in MOSS.
All documents stored in the document library inherit the permissions set to it, meaning
one can not set the permissions at document level.
 
My requirement is, I want to impose expire date at document level before uploading
to document library such that even if the document is downloaded on client machine after
expire date, user can not open the file.
Thus, is there any way to impose expire date on MS office files (excel/word/power point/
InfoPath) using C#?

Regards