Load X with the number 1
Store X into address $00
Increment X
Store X into address $01
Increment X
Store X into address $02
Increment X
Store X into address $03
Load X from address $01


If I'm right, that code would look like this:

LDX #1
STX $00
INC X
STX $01
INC X
STX $02
INC X
STX $03
LDX $01