Doing a clean install of Mavericks and installing iWorks 09 and the new iWorks for OS 10.9x I already have iWork 09 apps on my Mac's Mountain Lion installation.  I want to do a clean install of Mac OS 10.9x Mavericks on my machine.  This will wipe out the old iWork 09 apps and when I go to install iWork from the App Store it will be the new iWorks 2013.  But I also want to have iWork 09 on my clean installed Mavericks Mac.  Any suggestions for how to do this?  My license for iWork 09 is through the App Store.

Everyone keeps writing how the old iWork will be kept and the new iWork suite won't write over it.  However, this only applies if you're not doing a clean install, obviously.  However, I need to do a clean install and have both versions of iWork running on the new installation...
Or if it feels safer:
1)  make a clone or Time Machine backup of your current OS before upgrade. 2) Once you have the clean install working effectively, make a copy of your previous OS clone (call it Clone2)
3) Mount Clone 2, delete all applications except iWork 09 (and any others you want to port). 
4) Open Migration assistant and check 'Applications' only. Commit.

MA will now copy iWork O9 and its preferences / key to the new OS without affecting anything else.

Caveat(s): 
- This may overwrite iWork preferences for a later version - but generally not on Apple as they are named differently. For example, I have 4 versions of Apple iMovie on one of my Macs for old projects. 
- Bear in mind that porting an older programme over does not ensure that it will run well on the new OS. Make sure that the two are compatible first (forum search). There may be a soft hack to resolve an issue in some cases. For example, I like to run an older version of 'Text Edit' (with zoom control) from 10.6 under 10.8+ although I have to use a command line control to turn off its auto-save feature as this is now done through the OS. Without this it has a constant nag message 'you do not have permission to save this file'.