There are many different moving parts that could be licensed or purchased. It matter quite a bit which specific parts are being referenced in conversations about possible aggrements:
Likely licensing parts
-------------------------
1. The IP rights (the right to develop characters, places and content derived from the CoH universe, but not any existing code or art or tools)
2. The client rights (the right to use a current or former CoX client as shipped but not the source to it; *maybe* modification via data and scripting changes allowed for by the client's design, and plugging in custom models or art)
Likely purchasable parts (essentially buying part/all of Paragon Studios sources and tools)
--------------------------
3. CoH models and art (the characters, equipment, buildings, zones and instance sets)
4. CoH client engine, scripting and protocols (the client we use, and the communications between it and a server - it might use (3) or have to create and script its own models and art, and it might use (5) or have to create its own server
5. CoH server, database and behavior (the sum of behavior of the CoH server side)
Any deal for these parts should emphatically include any tools developed for use with them. Character modeling tools, test beds, traffic emulators, profilers, etc. Gaining access to parts of the codebase but lacking the associated tools would mean a giant setback in terms of time and effort.
--------------------
(1) and (2) would be minimally necessary to produce something remotely ressembling the CoH we know and love, or you risk C&D as mentioned. You would need to fabricate the server emulator either from scratch or using an existing emulation platform base. As most people know, emulating the server but using an existing client is what almost every private MMO effort does. Whether they formally obtain (1) or (2) is another story ...
I don't see gaining access to (3), (4) or esp. (5) unless you could convince them to actually sell Paragon Studios assets to you. And (5) along with internally developed tools would be the very last thing they may want outsiders to have, since it may be tech shared with other projects that they may yet repurpose in another subsidiary projects.
Regardless of which tact ends up being taken, you absolutely need a few very talented devs who have defintely built 3d games before (obviously ex-PS folks would be gold), in addition to the added talents of other devs pitching in for all sorts of contributions from building up the database of info needed to testing to scripting to limited UI mod'ing to protocol reverse engineering.
If you don't have access to the existing client, or lacking that the models and art assets, then you would also need a whole other set of talents - artists and character/zone designers - which would be prohibitive and best avoided (again, unless you could somehow get ex-PS folks).
----------------
TL ; DR
Unless you are going after the right to the CoH IP and existing client for use with your own server effort, you will need a studio-sized effort of your own. And even then you will still need a tight-knit set of dev resources not unlike Project99 (EQ), Feenix (WoW) or Utgarde (DAoC).