My advice would be to try and keep your customisations to a minimum.
I manually hack the templates and keep a log of what I've done so I can reapply it the next time I get a new copy of the templates. Generally my hacks have been either to fix bugs (which are quite often then fixed in SVN) or to the admin website (which I don't update from SVN anymore). It's not very rocket science, but I try not to change too much and its relatively quick.
Whist in the main development phase of my current project I would refresh my changes from SVN every couple of weeks and then reapply my changes, but now I'm at a stage where I need stable consistent generations so I've frozen the templates I use apart from any urgent bug fixes (which have been almost non existent!).
I'm sure I'll be at a stage soon where I can get the "latest and greatest" but I'll just have to reapply my hacks again.
If you want to do things like creating folders and other environment/system type tasks you might be better wrapping the gen in a NAnt or MSBuild script where you can do pretty much what you like.
What do you mean by "Can I add a property in an external file"?
Your last suggestion may be the best route to go if you're going to make many changes.
hth
swin
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Member of the .NetTiers team
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