No, since you are using Cash Account as your payment method, you have to pay the stock/ETF order using the same currency cash account. i.e., MYR denominated stocks have to pay from your MYR cash account, and USD denominated stocks have to pay from your USD cash account.

However, you are able to use 7 foreign Cash Account currencies available: SGD, USD, HKD, AUD, EUR, GBP, and CNY to perform Real-Time Foreign Currency Conversion into respective currency via Cash Account > FX Conversion available on FSMOne to fund for your stock purchase.