Reusing Commercial Disposable Kegs

[walrusdunne]

I've got an old freezer lying about and would love to build myself a keezer, but am always looking to save money. I've seen on here before people reusing the disposable kegs (from a brewery in Norwich?) and wondered how easy this actually is when it comes to refilling etc. The pub I work at has a couple of American sankey disposable kegs kicking about and I wondered if there was any information on how easy it is to reuse these. I don't have any pictures unfortunately but they are Founders All Day IPA 30L kegs and I believe the landlord mentioned they were either A or G type American keg fittings.
Thanks guys!