IVA and negative equity

This is now academic for me as I am out of my flat, failed the iva and preparing for bankruptcy..and haven't felt this relaxed in years..but out of interest, as a mate is in this position, what happens now in the the fourth/fith year of an iva when you are required to release any equity in your home to go to the debt?

I suspect most iva's were sold on the back of rising property prices so your house would pay off the debt, but with lending criteria now so tight and values falling, who's getting the money to do this? Are IP's linked in with money men who can provide the money at the right (ouch) price?

Will IVA's now run longer to recoup the shortfall?