I want to just obtain Hydrogen fueling parts and do this ourselves (myself) ??

On some engine parts and items for fueling - that would be illegal - a violation of the of the Anti-Tampering provisions of the Clean Air Act and you and / or your company would be hit with very stiff fines.  Only an Alternative fueling system manufacturer that builds and vends a complete system - which meets EPA FTP proof of fact requirements and accepts liability for the operation of the system may vend such a system.  See 40 CFR 85.535.   This is also why we can only license the system and can therefore revoke the license if we find out you have tampered with the system in violation of the agreement you entered into with us - and or as amended or supplemented - or the law as we have designed the system and vended it to you for use.  That is also why you can use ONLY our approved components as an alternative fueling system manufacturer OEM.  ( GM won't stand behind or support you trying to build and use your own ECM !!!)   That is also why we charge an annual license fee and periodically upgrade the parts of the system for you - with a lifetime warranty for EACH application you put it on.   This is also why we keep ALL communications in writing and through the website and it's database as product vending require a true VIN for each application and item we vend.   That is also finally why EACH VIN has a separate account under your company so we may know what parts have been replaced and what issues have arisen with that particular application / vehicle system.  .  This is all required and implied by the law.  See again 40 CFR 85.535.  This is a small price to pay for freeing yourself largely from the fuel pump.