You used to be able to just change the shortcut, but this doesn't work with EB1.0. The technique below does work (many many thanks juba1 !!)

here a easy way to play EB on BI (from LestaT)

Step One

1. Open Rome - Total War folder
2. Open EB folder
3. Open world/map/campaign folder
4. Rename imperial_campaign into barbarian_invasion
5. Open descr_strat.txt inside the barbarian_invasion folder
6. Find campaign imperial_campaign and change it to campaign barbarian_invasion
7. Save the file and exit the folder/s

Step Two

1. Open text folder
2. Copy and rename imperial_campaign_regions_and_settlement_names.txt into barbarian_invasion_regions_and_settlement_names.tx t
3. Save file
4. Open campaign_descriptions.txt
5. In the notepad (or any text editor) click;
a- edit
b- replace..
c- in Find what: box type IMPERIAL_CAMPAIGN_
d- in Replace with: box type BARBARIAN_INVASION_
6. Save and exit

Step Three

1. On the desktop, right-click on the EB shortcut
2. Left-click properties
3. In the target line, replace RomeTW.exe with RomeTW-BI.exe
* do not replace the whole-line, just the stated words above only.
4. Click apply and exit the box
5. Run the game....

Note: Just to add, this assume that prior to installing EB, you already have RTW and BI installed and patched to v1.6