If you just wana add Siyalan to the list of mountains you have climbed I would suggest you the Southern Route from Alamut(Haniz).But if you want a reall challenge you should try the Northern Route from Tonekaon.Trekking starts from eselmahalleh village in tonekabon and you will have a long long way to go.Full of nice places like ghorkhani,niardarreh,vinei, etc.
Hired a mule in the village of Haniz to help carry our backpacks to the 3870 m saddle where we camped. The next day, climbed Siyalan and bagged Kandigan Peak and then descended the very long northern slopes. By dusk, had not found a flat area to set up our tent so ended up sleeping in the open forest. Got some drizzle but fortunately no down pour. On the third day, hiked to Asal Mahaleh.