I made some aliases and binds to help execute MP changes w/ one keypress while your in the heat of battle http://www.alliedassault.com/ubb/smile.gif
Paste the following into your custom.cfg in your MOHAA/main directory:

***Start copy***

// Quick Weapon Change
// Rifle (Garand, Mauser)
alias getrifle "primarydmweapon rifle"

// Sniper Rifle (Springfield, KAR 98)
alias getsniper "primarydmweapon sniper"

// Sub-Machine Gun (Thompson, MP40)
alias getsmg "primarydmweapon smg"

// Machine Gun (BAR, STG44)
alias getmg "primarydmweapon mg"

// Rocket (Bazooka, Panzerschreck)
alias getrocket "primarydmweapon heavy"

// Shotgun
alias getshotgun "primarydmweapon shotgun"

// Quick Team Change
// Allies
bind a "join_team allies"

// Axis
bind x "join_team axis"

// Spectator
bind s "spectator"

***End copy***

The weapon changes may be most useful on FFA and Team-Based maps.. not so much on Objective unless you have the respawn mod installed or playing Omaha.