Efficient exploitation of the aggregate resources available to a researcher is a challenging and real problem. The challenge becomes all the greater when researchers who collaborate across functional or administrative domains need to pool their disjoint heterogeneous resources to achieve their objectives. Support tools are becoming available for these ad hoc resource integration and sharing scenarios. The focus of this paper is the identification of suitable deployment and usage strategies when using the workflow approach with these tools. In particular, we present a novel two-level peer-to-peer model for dynamic resource aggregation that operates entirely at the user level. This sidesteps the need for system level middleware and administrative support. This paper presents our strategy, the underlying framework and the workflow expression and evaluation semantics.