found an answer. there is a command line switch to select your directory:
Q7: How do you control the location of the \MSOCACHE folder?
A7: To specify the location of the \MSOCACHE folder, use the LOCALCACHEDRIVE setup property. This property can be enabled from a command line or a Setup settings file (Setup.ini).
Note You cannot control the location of the \MSOCACHE folder in the Setup user interface.
oops i should have posted the command. in a run box type:
change F to the letter of your cd-rom drive that the office2003 CD is in.
C is the drive letter to install the files to, replace C with the drive you want the destination at. you should also be able to specify sub-directories, example c:\program files\.....ect