Besides, Rick's tools, I think you can still find the RoboMIF plug-in for FM (converts all FM files in a book to MIF) at: http://download.macromedia.com/pub/robohelp/files/downloads/htmlhelp/robomif.zip
You can also try Datazone's freebie DZbatcher tool to create a batch file for this. See: http://www.miramo.com//english/overview/download.html
And, in addition to all these other fine suggestions, I'll point out that this could be a very simple script, especially if all files are in the same folder. You might talk somebody into doing it for a low price or even free, although it sounds like you don't have time to wait.
There are some free ExtendScripts available.
From Klaus Daube:
From Rick Quatro:
Or this commercial FrameScript from itl:
http://www.i-frame.itl.info/en/feature-description/i-frame-modules/translation-pack/conver t-fm-to-mif-mif-to-fm.htmlhttp://www.i-frame.itl.info/en/feature-description/i-frame-modules/translation-pack/conver t-fm-to-mif-mif-to-fm.html
I contacted Rick at frameexpert dot com, explained my situation and his script was exactly what I needed. Being able to contact him directly was very helpful in the decision to purchase his script. Processed all 920 .fm files in just under 5 minutes.
Thank you Jeff_Coatsworth for the referral.