Start by understanding the data structure of xkcd. The xkcd website provides a JSON API for each comic. You can access the JSON data for a specific comic by appending the comic number to the URL `https://xkcd.com/{comic_number}/info.0.json`. To extract all available data, you’ll need to iterate over the comic numbers starting from 1 up to the latest comic number. Use a scripting language like Python to automate this process, and store the extracted data in a local file or a temporary database.

Ensure that you have ClickHouse installed and running. You’ll need access to a ClickHouse client to execute SQL commands. You can use the ClickHouse command-line client or a GUI client like DBeaver. Make sure that the necessary ports are open and accessible if you are running ClickHouse on a remote server.

Determine the schema you want to use in ClickHouse for storing xkcd data. Create a table in ClickHouse with appropriate columns that match the JSON fields from xkcd. For instance, fields like `num`, `title`, `img`, `alt`, and `date` (a combination of year, month, and day) might be part of your table schema. Use a SQL command similar to the following:
```sql
CREATE TABLE xkcd_comics
(
num UInt32,
title String,
img String,
alt String,
date Date
) ENGINE = MergeTree()
ORDER BY num;
```

Convert the JSON data you have extracted into a CSV format that can be easily ingested by ClickHouse. You can use Python’s built-in libraries such as `json` and `csv` to parse the JSON and write it into a CSV file. Ensure that the CSV columns match the ClickHouse table schema.

Use the ClickHouse client to load the CSV data into the ClickHouse table. You can use the `clickhouse-client` command line tool for this purpose. The command might look like this:
```bash
clickhouse-client --query="INSERT INTO xkcd_comics FORMAT CSV" < xkcd_data.csv
```
Ensure the CSV file path is correctly specified and accessible by the ClickHouse server.

Once the data is loaded, verify that the data in ClickHouse matches the xkcd data. You can do this by running simple SELECT queries to check the number of rows, unique comic numbers, and some sample data points to ensure everything is imported correctly.
```sql
SELECT COUNT(*) FROM xkcd_comics;
SELECT * FROM xkcd_comics ORDER BY num DESC LIMIT 10;
```

Comics are released periodically, so automate the data extraction and loading process. Set up a cron job or a scheduled task that periodically checks for new comics, extracts data, transforms it into CSV, and loads it into ClickHouse. This ensures that your ClickHouse warehouse remains up-to-date with the latest xkcd content.

By following these steps, you can effectively move data from xkcd to a ClickHouse warehouse without relying on third-party connectors or integrations.