Set game mode = Melee
Wins = 8 (this gives you maximum amount of tries before taking you back to main screen)
Stage = Trucks
Walk over to the back door of the trucks and as the doors swing from being open, as they swing back closed again time it so that you can drop down and grab the inside of the door using
/
and it will swing you inside the truck, once inside let go.
The Achievement guide below will walk you through this achievement and all 18 others achievements in the game too including an easy method for getting the most difficult one in my opinion (Sit Down achievement).
Timestamps are shown below the video.ACHIEVEMENTS LIST TIMESTAMPS:0:00 Intro and game set up
0:35 - Welcome to Beef City Achievement
1:30 - Safety Warning Achievement
2:35 - Bucket List Achievement
3:15 - Roast Beef Achievement (demonstrates how to climb and fight as well)
6:05 - Sea Legs Achievement
7:27 - Buoy o' Buoy Achievement
8:30 - In Transit Achievement
9:10 - Keep on Trucking Achievement
10:00 - Long Haul Achievement
11:12 - Self Storage Achievement
12:12 - Special Delivery Achievement
12:58 - Ground Floor Achievement
14:30 - Hang Tough Achievement
17:09 - Step Down Achievement
18:08 - Drop Kick Achievement
18:08 - Short Wave Achievement
19:35 - Big Head Achievement
19:35 - Shutout Achievement
21:10 - Sit Down Achievement