1. Follow this instruction to install Telegram X
2. Remove your default Telegram app
3. Check MTProto Proxy channel for proxies
4. Choose the nearest proxy and connect

You can change proxy settings and switch between proxies via shield button in right corner of Telegram X screen.

You can get proxy settings from other bots, e. g. @proxy_service_bot provides socks5 proxy.

UPD 18.06.2020:
You can use this proxy created by me.