For portable apps, I assume they don't have complex registry settings. If so, you can simply install the apps to your windows 7 host. Then inside xp mode vm, you can simply click the executable files to launch them.
In your xp mode vm, you should see some shared drives, such as "C on host", here you can access host folders. For example, you can browse to host c:\program files (x86)\your app, then double click the exe to run it.