First of all, you should outline your requirements: it could be a precise description of the dedicated resources you need including their expertise, seniority level, location, and cost. Otherwise, you can briefly describe the project and the problems you have. Then, you should contact a professional development agency that provides dedicated team services. Get in touch with as many agencies as you like.
Once you have established communication with some companies, the process will be pretty much the same:
1. An intro call to discuss your needs;
2. You get several CVs of dedicated resources;
3. You interview the pre-vetted specialists;
4. Agree on terms and sign contract;
5. Onboard your dedicated team.