Hold off on writing the script...Unless you want to of course.
Casper is correct. Here's a portion of the keyboard.txt file found in your userdata/settings folder.
train_dcc_down x, comma
train_dcc_up w, fullstop
train_dcc_stop s, slash
train_dcc_handbrake a, apostrophe
train_cabin_brake_release q, KP9, KPPgUp
train_cabin_brake_lap z, KP6, KPRight
train_cabin_brake_application a, KP3, KPPgDn
train_cabin_brake_emergency pause
train_cabin_brake_1 null
train_cabin_brake_2 null
train_cabin_brake_3 null
train_cabin_brake_4 null
train_cabin_brake_up null
train_cabin_brake_down null
train_cabin_indbrake_toggle e, KP4, KPLeft
train_cabin_indbrake_bail d, KP0, KPIns
Press the A key. Z is for lap brake.
John