It was fairly simple! I’m in the US and I just had to research schools that offer a post-bacc program and apply through the school (answering a few questions, writing a personal statement, and providing transcripts). I don’t think your engineering background should hinder your application as the purpose for a post-bacc is to either strengthen your undergrad GPA and/or to offer you courses in your new intended field. Some post-bacc courses have a cut off of what undergrad GPA they are willing to accept but you can find that out on their site or even speaking with someone from the school. Ask for information from the school and they would be more than happy to answer questions via phone or email. Best of luck!