I don't have a data2.cab in my XSI installation - only data1.cab.
Did you get as far as registering your mod tool installation? After installation, you MUST register it with Softimage for it to start up. Back when I installed it (long time ago), immediately after the first startup, you have to do a File-Save and a registration screen pops up. Fill out the registration (you'll get spam from your email address so be prepared), submit the form and you'll get an email with a registration code which you then need to use after you restart XSI to get anything(!) to work.
FYI - my installation of the the mod tool always requires an active internet connection and it will hang on the splash screen if your connection is borked or the Softimage server is slow.
For me, with 1 G RAM, 4G CPU and 512k cable, XSI takes about a minute to start up.
Softimage has a forum site for the mod tool (don't know whether it's still up) and you can get some help there.
IMO, using other than XSI to model is a pain in the rear. With XSI, you export your file and after one drag and drop on a desktop shortcut, the model's ready for use.