easiest way is just to call the company you want to be sponsored by and talk to them. most are pretty willing to help out, they usually have set amounts that they have to spend that way for taxes and stuff like that. doesn't hurt to have some type of recognition ahead of time either.
Spend ALOT of your own money modding the car .... take it to ALOT of show... win trophies at ALOT of them ... THEN talk to companies about sponsorships. Be prepared to have a FULL PROPOSAL written up for them!
My bf had several sponsors for his cougar ... Ive learned alot