The best way to do this within the IIQ framework would be to represent those “projects” as entitlements in your entitlement catalog. Once you have that, you can then have a Field in your ProvisioningPolicy which is of type ManagedAttribute and filters on ManagedAttributes (entitlements) from that application that are of type “project”.
If you are using a Web Services or JDBC connector for example, you could set it up to aggregate the projects as entitlements that are associated with the account objects that are aggregated by the connector as well.