Although we dont split ur install over two different periods, we do copy all the office 2010 files to c:\temp\ folder and then install using a autoit script - i dont see why this wouldnt work split into your method.
If you think of the tasks that are needed:
1) Put all setup files into a folder on your appshare
2) create an admin (msp) file by running the setup.exe /admin command (http://technet.microsoft.com/en-us/library/cc179097.aspx)
3) save the msp file in the updates folder of the office2010 installation
4) copy all install files from appshare to c:\temp\office2010
5) run c:\temp\office2010pro\setup.exe (no need for anything else as it looks into the updates folder automatically)
6) delete the local cache (remove c:\temp\office2010)
And then logically split them:
Function 1 (Tasks 1 to 4) - Copy setup files from appshare to local temp directory - 1st batch file\autoit script to do this.
Function 2 (Tasks 5 and 6) - Install Office and remove local temp directory - 2nd batch file\autoit script to do this.
Hope this helps