The talk will include the alleged border encroachment that led to violent clashes between Cambodian lawmakers and villagers and Vietnamese border security agents on Sunday.
Opposition officials expect the new station to be up and running by the end of 2015, if they can find the money.
Voter registration, which in the past has seen many opposition supporters disenfranchised, will begin in October.
Some 400 NGOs have joined together in a campaign to halt the law’s passage, demanding instead that it include consultation from them before going forward.
Kem Sokha, vice president of the opposition party, told reporters his party will do its best to make sure concerns from NGOs are heard while the law is debated.
The ceremony will be attended by government officials, foreign dignitaries and King Norodom Sihamoni at Wat Botum pagoda, in Phnom Penh.
Human Rights Watch has implicated Chea Sim—who was head of the ruling Cambodian People’s Party and president of the Senate—in serious crimes under the Khmer Rouge.
Speaking to supporters in Preah Sihanouk province on Monday, Sam Rainsy expressed his support for the “good deed” and said it was a sign of improved relations between the Rescue Party and the CPP.
Chea Sim had been a counterweight to Hun Sen’s power within the party.
Chea Sim’s passing may also open the way for Prime Minister Hun Sen to improve ties even further with China.
The NGO law seeks to regulate the thousands of organizations in the country, but critics fear it will become a tool to silence government criticism.
Officials of the Cambodian People’s Party told VOA Khmer that Hun Sen will take over as president of the party, keeping in line with decisions made at a party congress earlier this year.