I just had mine changed. I too have read about there not being a gasket but my new manifold came with one. The install is pretty straight forward if you are comfortable removing the air intake, hoses etc. Just remember to spray the bolts with WD40 or similar the day before as they will be pretty tight on there.
I was going away for a couple of days so I got my local garage to change it for me while I was away but its not a tough job to do yourself.