[XxAvalanchexX]

You could just add the knife level between each weapon. Example:

gg_weapon_order "glock18,knife,usp,knife,andsoon..."

Note that you have to specify the amount of kills with the knife, because by default it is always 1.

Although, you can only have a max of 32 levels, so you'd have to compromise. But I don't see myself adding this as a feature.