Not tried it but:
Add a Webviewer to your app
Set the HomeURL to
https://paypal..... for which ever locale is correct - i.e. .com, .
co.uk or .fr (you may need to do some extra work here to collect the locale from the user to make up the url)
Create a button to get the webviewer going
See if you can access paypal OK in the webviewer, login etc.
Customise to your liking