I would love it if you could - that's on my wish list, but we haven't been able to get that programmed in yet. I'm hoping we'll be able to do it next year...so not soon enough for you. Yes, you'll have to enter manually. :(
If you want a system to provide you with random questions, you can buy the extra question pack that goes along with GMATPrep. It costs $30 and includes about 200 quant and 200 verbal questions, along with some IR questions. You can set that to give you random problem sets. You choose # of questions, difficulty bucket (easy, medium, hard, or some combo of the three), and question type (eg, DS, PS, or both).
Also, here's an article that talks about how to create mixed problem sets out of OG problems in general:
https://www.manhattangmat.com/blog/inde ... blem-sets/