If you are asking how the actual Form 3115 is filled out to 'catch up' on the missed depreciation', you may want to Google "Brass Tax 3115".  That tax preparer has a nice guide for sale for $20 that many have found extremely helpful.

After you calculate the missed depreciation, you can generally just enter that as an 'other' expense on the appropriate form (in your case, that sounds like 8829).