human interaction

hello,

we run a sap portal and now we want to create some workflows with and without human interaction using the exchange infrastructure (xApps).

my question:

is it possible to create workflows with human interaction which could be done in the portal. does the exchange inf. support this?

(i know that ad-hoc workflows are supported by the portal)

but what is with business workflows and cross-component BPM? any idea?

help would be great.

regards daniel