Download here hl booster.rar , unzipp it (directly in addons or copy the booster folder in HLDS\cstrike\addons, (HLDS is the directory where you have the server), then edit in HLDS\cstrike\addons\metamod\plugins.ini, the line:win32 addons\hlbooster\dlls\booster_mm.dll. Very important!!!! In order to work, in the HLDS\cstrike\server.cfg you have to write the next line:

exec addons/hlbooster/hlbooster.cfg