Use the original definition and have the DRC firmly allied to the Capitalists
It was firmly allied to the capitalists.
Alright, first things first, Mobuto has to be sane. If he's the arrogant wanker of OTL he'll overthrow Lumumba and everything will go wrong from there. While we're on the subject, Lumumba has realise the weakness of his position, he's not that powerful, he's in dangerous territory. Pissing of the Americans will not work well and pissing off his ministers will work worse. The name of the game is
softly softly.
Secondly, have him pick principled, yet charismatic individuals who will get rid of the stealing fuckwads that were there in the beginning, and who will do their job diligently and who will talk back to him when he comes up with a bad idea.
Thirdly, NO FUCKING ARMY. The standing army was the bane of the newly-independent African country, it existed only to abuse the people; overthrow the government and be a hole for corrupt military generals to dig money out of. Instead of having an army, Mobuto spends time training up a police force instead. The military begins five years in, no sooner.
Fourthly: No big projects. What the DRC needs is small, local building projects to foster relations between various isolated communites, roads, railways etc. Big dams and huge, unnecessary hydroelectric plants are good for dickwaving but not much else, especially when the majority of your populace is uneducated and will have their livelihoods destroyed by flooding.
Fifthly: Education, education education. This is a poor country gentlemen, we need trained scientists, engineers, mathematicians, computer scientists and programmers ASAP.
Five years in, and things should be rolling along nicely. Unfortunately, that's when the Katanga secession will start up. Not to mention the whole, Rwanda situation.