Play animation with blend-in/out from Unrealscript

In my weapon class (that deals with the players arms and held weapon) I have a PlayWeaponAnim() function that looks something like this:

simulated function PlayWeaponAnim(name AnimName, float Rate, optional bool bLooping)
    local AnimNodeSequence AnimNode;

    AnimNode = GetWeaponAnimNodeSeq();

    if(AnimNode.AnimSeq == none || AnimNode.AnimSeq.SequenceName != AnimName){

    AnimNode.PlayAnim(bLooping, Rate, StartTime);

The thing I can’t figure out is how to add a blend in and out when playing a new anim. Could anyone offer any advice?

Thanks in advance.

I isually have an AnimNodeSlot in my animtree, and that one I reference from code to play my animations. that one has blend-in/out as params

Thanks for the response @Chosker. Yeah I also have the same for all my pawns, but when I built my base weapon class I didn’t use an animtree. It seems like I should be able to blend using an AnimNodeSequence, but maybe I can’t.