You could use an external preprocessor such as my free PPWIZARD (this is what I do).
I have actually created a NSIS add-on (on PPWIZARD download page) for this tool which simplifies the creation of install packages (for example it does ALL uninstall stuff for you - by default). It also by default chooses a version number for you based on the date but it could be picked up (extracted from doco etc) from anywhere.
There have been quite a few downloads of the header but no feedback. Please email me if you have tried it and liked or not liked it. It's biggest fault is no doco but the sample is good for starting with.
For more details/downloading please go to: