It does not take long to learn AR, AP and GL modules in the ERP system. The most important is if you truely understand the accounting concepts. Many companies are willing to train the ones without ERP background and many people learn ERP in their jobs. Cost accounting is more complex. Manufacturing experience is always a plus.
Once you work in the ERP sytem, the next thing is how you learn. If you just want to do the data entry, it is easy.
If you want to understand accounting modules throughly, my recommendation is to read the ERP instructions, not just accounting department's but purchasing, receiving, QA, sales, shipping even planning and engineering's, etc. Try company's test data base if there is one. Accounging is the ERP end user. Many manufacturing transactions are transalated into accounting language. If you understand the accounting concepts, you can put them together.You will understand what I meant if you have the chance to be exposed to accounting set ups. No ERP system is perfect. You learn ERP in the practice.
You may use SQL and Hyperion to generat different reports. In some companies, the reports are done by the IT dept or experts. If not, you will learn SQL and Hyperion techniques and utilize your ERP knowledge to pull the data from the right table and spot.
No matter what, ERP system is just a tool. Don't be scared if you do not have the background. It makes your resume more impressive if you have some ERP training. Anyway, do not feel shy to show the employer you are a communicator, quick learner, team player, hard worker, a person they can trust....
Be confident and good luck!