I'm taking the same path. I'm in my Junior year as a Chem. major and will transfer to another University upon graduation (my school has no chemical engineering degree) to pursue a MSc ChEn. It's possible to do because most Chemistry majors take the same classes for their first two years as a ChEn major. You'll have to play catch up with the Engineering courses and whatnot, but it looks possible to complete within two years (assuming a full load each semester and summer classes). Below are the undergraduate pre-reqs I will have to complete before going on to a Master's in ChEn. Hopefully it will give you some insight to what choices you could make.
CHEN 2100/2101 Principles of Chemical Engineering and Lab
ENGR 2010 Engineering Thermodynamics
CHEN 2610 Transport I – Fluids and Fluid/Solids
CHEN 3370 Phase & Reaction Equilibria
CHEN 3620 Transport II – Heat and Mass Transport
CHEN 3700 Chemical Reaction Engineering
CHEN 3650 Analysis
CHEN 3660 ChE Separations
CHEN 3820 ChE Lab I
CHEN 4450 Process Economics
This is all assuming you have already taken General Physics, Calculus and Differential Equations, General, Organic and Physical Chemistry, and Computer Science to attain your Chemistry degree.
Hope this helped you out. Where abouts are you located at? I may could give you some references.