Just talk to your sales person. Your allocation will purely be a function of how much comissions you have paid. Keep in mind the average ipo is priced to pop around 15% on day one, so most IPOs allocations are almost considered free money, especially hot ones. IPOs are just a form of comissions rebate.
U can try to also convince then that you are a long term investor, since companies prefer not to have flippers buy their stocks. However, this doesn't make much difference