app.project.activeItem.selectedLayers[0].blendingMode = BlendingMode.ADD;
List of available values. You can use either the text OR the number.
BlendingMode.ADD – 5220
BlendingMode.ALPHA_ADD – 5244
BlendingMode.CLASSIC_COLOR_BURN – 5219
BlendingMode.CLASSIC_COLOR_DODGE – 5225
BlendingMode.CLASSIC_DIFFERENCE – 5234
BlendingMode.COLOR – 5238
BlendingMode.COLOR_BURN – 5218
BlendingMode.COLOR_DODGE – 5224
BlendingMode.DANCING_DISSOLVE – 5214
BlendingMode.DARKEN – 5215
BlendingMode.DARKER_COLOR – 5247
BlendingMode.DIFFERENCE – 5233
BlendingMode.DISSOLVE – 5213
BlendingMode.DIVIDE – 5249
BlendingMode.EXCLUSION – 5235
BlendingMode.HARD_LIGHT – 5228
BlendingMode.HARD_MIX – 5232
BlendingMode.HUE – 5236
BlendingMode.LIGHTEN – 5221
BlendingMode.LIGHTER_COLOR – 5246
BlendingMode.LINEAR_BURN – 5217
BlendingMode.LINEAR_DODGE – 5223
BlendingMode.LINEAR_LIGHT – 5229
BlendingMode.LUMINESCENT_PREMUL – 5245
BlendingMode.LUMINOSITY – 5239
BlendingMode.MULTIPLY – 5216
BlendingMode.NORMAL – 5212
BlendingMode.OVERLAY – 5226
BlendingMode.PIN_LIGHT – 5231
BlendingMode.SATURATION – 5237
BlendingMode.SCREEN – 5222
BlendingMode.SUBTRACT – 5248
BlendingMode.SILHOUETE_ALPHA – 5242
BlendingMode.SILHOUETTE_LUMA – 5243
BlendingMode.STENCIL_ALPHA – 5240
BlendingMode.SOFT_LIGHT – 5227
BlendingMode.STENCIL_LUMA – 5241
BlendingMode.SUBTRACT – 5248
BlendingMode.VIVID_LIGHT – 5230
By now you may think I am a wizard :D. Actually, I use this document a lot. Just go in, search blending mode. I, however, came up with the number values with my own method. So I am half a wizard.
Take care!