Yes, it is possible, you would have to define < as, for example, button 1 and > as button 2.
Then, depending on how you want the weapons to work, the following is different. If there is no visible difference in the player sprite when changing weapons (only difference is in bullets that the player fires), then all you have to do is have two special functions. One that adds 1 to an inventory that keeps track of what weapon you're on, and one that subtracts one from the same inventory. Setting the "Reset to Opposite Limit" option would be a nice way to not limit how far you can go.
Then, when shooting, just check to see how many of that inventory you have, and accordingly create the proper bullet sprite. This may be a little difficult, because the way inventory works is that if you have AT LEAST 1, then it will activate a function that requires 1 of said inventory. However, there are several ways to get around this.
One is to have each different type of bullet be defined as a class "Bullet" and a different template, then, have a collision defenition between two bullets that activates special function COL_<A_Template><B_Template>*. Then create special functions called COL_Bullet1Bullet2 and COL_Bullet2Bullet3 and COL_Bullet1Bullet3 etc. (if the names of your bullet templates are Bullet1 Bullet2 Bullet3 etc.) and they would remove all of the first type of bullet from the map. (i.e. COL_Bullet1Bullet2 would remove all of Bullet1).
Another way is to have each bullet a different class, and then just define each collision between the bullets (Collision between Class Bullet1 and class Bullet2), then just destroy Sprite A.
Yet another way is to have many many more special functions and inventory items. Pressing ">" would instead have 4 special functions associated with it. Each would require 1 inventory of a different type. Here, let me just show you:
Activation Parameters: Pressing Button 1
Requires (1) Weapon1Inv (Use it up)
Action: Add 1 to Weapon2Inv
Activation Parameters: Pressing Button 1
Requires (1) Weapon2Inv (Use it up)
Action: Add 1 to Weapon3Inv
Activation Parameters: Pressing Button 1
Requires (1) Weapon3Inv (Use it up)
Action: Add 1 to Weapon4Inv
Activation Parameters: Pressing Button 1
Requires (1) Weapon4Inv (Use it up)
Action: Add 1 to Weapon1Inv
Activation Parameters: Pressing Button 2
Requires (1) Weapon4Inv (Use it up)
Action: Add 1 to Weapon3Inv
Activation Parameters: Pressing Button 2
Requires (1) Weapon3Inv (Use it up)
Action: Add 1 to Weapon2Inv
Activation Parameters: Pressing Button 2
Requires (1) Weapon2Inv (Use it up)
Action: Add 1 to Weapon1Inv
Activation Parameters: Pressing Button 2
Requires (1) Weapon1Inv (Use it up)
Action: Add 1 to Weapon4Inv
Then when firing, each function would just check for 1 inventory of whatever type and create the propper bullet.
However, this would be immensely easier with scripting. There are many resources to help you learn how. I really, really reccommend you try learning just a few beginning scripts. The help that comes with SGDK, the sample scripts on sourceforge, and the people on this forum will help if you get stuck or need help.