Only to a point and with a lot of effort. The usage must actually be different. You can not for example use both connection to play the same game. You could though use one to play the game and the other to connect to a voice com server.
This is all done via the ROUTE command. The hard part is getting the lists of IP you want to use the secondary connection. You are going to have to key them all in which is where all the work comes in. If you can keep it to a small list it will work.
Be careful though 4g connections tend to have many limitations on them the largest being caps on bandwidth usage.