in 1.2.3 there isnt one, in open beta 1.3 follow the following steps:
i. make sure u can access ur console. if u can't add '-console' to ur shortcut
ii. start a map and enter 'sv_cheats 1'
iii. type 'restart', this will reload the map
iv. choose a char and then enter 'powerlevel xxxxxx' where xxxxx is where u put ur desired pl