void CGameMovement::DodgeLeft( void )
{
	if(gpGlobals->curtime <= m_flDoubleTime)
		{
		int i = 0;
		Vector EndPoint;
		trace_t tr;

		float flMul;
		if ( g_bMovementOptimizations )
		{
		#if defined(HL2_DLL) || defined(HL2_CLIENT_DLL)
		Assert( sv_gravity.GetFloat() == 600.0f );
		flMul = 228.0f;	// approx. 21 units.
		#else
		Assert( sv_gravity.GetFloat() == 800.0f );
		flMul = 268.3281572999747f;
		#endif

		}
		else
		{
		flMul = sqrt(2 * sv_gravity.GetFloat() * GAMEMOVEMENT_JUMP_HEIGHT);
		}

		//if(gpGlobals->curtime <= m_flDoubleTime)
		//{JUMP = 3;

		for(i = 0; i < 2; i++)
                EndPoint[i] = player->GetAbsOrigin()[i] + m_vecRight[i] * 24.0f;

            UTIL_TraceLine( player->GetAbsOrigin(), EndPoint, MASK_SOLID_BRUSHONLY, NULL, COLLISION_GROUP_NONE, &tr);
           
                for(i = 0; i < 2; i++)
                    mv->m_vecVelocity[i] = m_vecRight[i] * -275 * 1.1;

                mv->m_vecVelocity[2] += flMul;    // Jump!
				mv->m_nOldButtons |= IN_MOVELEFT;
	}
	else
	{
	m_flDoubleTime = gpGlobals->curtime + 0.5f;
	mv->m_nOldButtons |= IN_MOVELEFT;
	return;
	}
//}
}

and in game_ui.cpp

if ( pPlayer->m_afButtonPressed & IN_MOVELEFT )
	{
		CGameMovement *DDodge = new CGameMovement();
		DDodge->DodgeLeft();
		m_pressedMoveLeft.FireOutput( pPlayer, this, 0 );
	}