You will have to face long queues to enter and leave Belarus, and if you bring own guns it will be really painful - prepare to stay locked for up to 4-5 hours for customs controls. We will send our representative to assist in customs formalities for firearms importation, to be met in Poland or Lithuania, you will have to assure a seat for him in your vehicle on both way.
And then, you will have to pay for the roads.
The official information about toll roads in Belarus can be found on the website of handling company - Beltoll.
First of all - don't try to pass on paid roads without paying - they will stop you, if not at the moment they will do it later, but they will. You will pay 100 Euro per each passed control point which are found every 10 km or even more frequently.
Now you can buy an electronic vignette - 18 Euro per 15 days, arranging it before arrival to Belarus
The vehicle's owner (or the person who imports it) should be the only one to drive it in Belarus, no other persons are allowed to do this.